Katsu fish pie

This Japanese-influenced katsu fish pie is a reworking of the British comfort food classic. Brimming with a mix of fish and seafood with a creamy béchamel subtly infused with with the flavours of katsu curry, a Japanese comfort food increasingly popular around the world, it's topped with a sweet potato and a panko crust.

Jump straight to the ingredients and cooking method

It's become a little tradition of my own that every year I create a remix of that stalwart British comfort food, fish pie. Usually I do so in the spring, but this year I have been late out of the gate, primarily for the time I have taken developing it to get to a recipe I was satisfied works well.

While easy to cook, I won't mislead and say it's a "quick meal": British fish pie involves a number of separate stages and cooking processes. But, one of the reasons homemade fish pie remains so popular in the UK is that you can take it at a leisurely pace, completing the first stages a day (or more) in advance before popping the assembled fish pie into the oven and getting on with other things.

Big in Japan

This year, I've gone for a Japanese twist. Thinking about the spin I might want to put on this year's outing, it seemed a natural evolution. A baseline British fish pie consists of cooked white fish in a béchamel sauce—which many British people call "white sauce"to my chagrin—topped with mashed potatoes and cooked in the oven until the potatoes form a crisped crust. Over the years, fancier versions have emerged such as those including a mix of fish and seafood or using what is effectively a Mornay sauce rather than a plain béchamel. Although definitely a well known and much loved British comfort food, it is not nearly as "traditional" as most British people think, having only appeared in this form after WWII. I'm not going to repeat that whole history here, but if you are interested, you will find it here, on the page for one of my earlier versions of fish pie.

So, I thought it fitting to create a katsu curry version because, like fish pie, Japanese katsu curry is also a comfort food and also one that is not nearly as traditional as some assume. There is also an additional British connection, namely the British Royal Navy.

With its strong colonial connections to India, Britain was the first European nation to see Indian culinary influences in cooking across broad sectors of British society from the mid-19th century onwards. The Royal Navy particularly liked curry and rice—or their interpretation thereof that involved meat, potatoes and a thicker gravy than common in Indian dishes—because it created a tasty, hearty dish that was easy to knock up in large batches in the cramped conditions of galleys on naval vessels.

At some point during the Meiji Restoration (1868 -1912) the British Royal Navy's frequent contact with Japan introduced Indian masalas to the Japanese. The most florid version of the tale is that it was a group of shipwrecked British sailors washing up on the coast of Japan—conveniently with their provisions—who introduced the locals to these flavours.

But, given the Japanese Imperial Navy later followed the British penchant for curry at sea, I think it far more likely the routes of sharing these flavours were maritime. During the Meiji era, the Royal Navy was much admired by the Japanese. It was a period of rapid modernisation for Japan and the Royal Navy often came into contact with its Japanese counterparts as they helped train and shape Japan's new, modern navy. Knowing from personal experience exactly how food is a point of connection between sailors from different nations, I suspect "Japanese naval curry", this combination of curry with rice (kare raisu), came about through sailors sharing tales and complaints about grub at sea.

"...the vast majority of Japanese households creating a katsu curry sauce will not make it from scratch..."

This was merely a precursor to today's katsu curries that, like British fish pie, are clearly more of a post-WWII phenomenon. As with yakisoba, there were stages in this evolution. We know that tonkatsu, the breaded pork fillets that today are often served with katsu curry sauce, were adopted by the Japanese from the Schnitzels of Austrian and Swiss cooking and sold in Japan from as early as 1899 at the Rengatei restaurant in Tokyo's Ginza.

But, the style of serving katsu that we know today—fillets of pork or chicken fried in panko crumbs and served with rice and a katsu curry gravy—didn't really emerge as a popular Japanese comfort food until the rebuilding of Japan post-WWII. One colourful legend attributes its birth to Shigeru Chiba in 1948. He was a prominent professional baseball player, a regular at a Tokyo yōshoku (Western-influenced food) restaurant called Ginza Swiss. When he complained about the hassle of ordering katsu and curry separately, supposedly the chef started immediately combining them on the same plate.

But, it's not only how it was served that evolved. The Japanese method of making the thick katsu curry gravy—very possibly based on versions of curry created by British Royal Navy cooks—involves making a milk-free roux of oil or butter and flour. Roux is not used in Indian cooking of what gets called "curry" elsewhere. Similarly, the curry powders most commonly used contain similar ingredients to a mild Madras-style masala—turmeric, cumin, fenugreek, chilli, garlic, mustard seeds, etc. Again Madras masala was invented for the British market and is not something really used in India. The Japanese also worked in things not found in Indian curries such as orange peel (or yuzu), higher quantities of ginger and even honey, giving this mild curry a subtle sweetness.

One block or two?

By the late 1960s, when katsu curry sauce was already an established menu item in many yōshoku eateries, food manufacturers started producing readymade versions for home use, from the microwaveable to boil-in-the-bag versions. These days, the vast majority of Japanese households creating a katsu curry sauce will not make it from scratch but use readymade blocks of curry sauce roux, often marketed in the West as "golden curry sauce blocks", since, technically "katsu" refers to the meat fillets, no the curry gravy.

For this dish, I am using one of these mixed into the béchamel. The two biggest brands of these are House Foods, which dominates the Japanese domestic market, and S&B Foods, which has focussed on international markets in addition to being the second biggest brand in Japan. Wherever you are, you should be able to get your hands on one of them in supermarkets, specialist Asian stores or online. In the case of S&B Golden Curry, these blocks come in packs for five portions, conveniently marked out on the packaging.

Having developed this recipe, I can now assert that I think one of these portions, i.e. one fifth of the overall block produces the optimal flavour. Obviously, if you want to use more for a more pronounced katsu curry flavour, that's your call.

An advert by Otsuka from the late 1960s, one of the first companies to produce microwaveable readymade curry products in Japan with their Bon Curry range.

The sweet zone

I am using sweet potato rather than the traditional potato topping of a British fish pie. This is already something health-conscious hipsters have been doing for quite some time because of the lower carbohydrate content. But, for me, I'm doing so because it maps onto a fusion version of Japanese flavours and for more practical reasons.

Japanese sweet potato (satsumaimo) is a commonly used ingredient, most famously for yaki-imo; Japanese sweet potatoes slow-roasted over hot coals and sold as a street food. Japanese sweet potatoes have slightly less starch than predominant varieties elsewhere. You may be able to find them in specialist Asian stores—sometimes marketed as "Asian yams" (which can be confusing because they are not the same thing as Japanese yams) —but Japanese and other sweet potatoes are very similar and I'm using bog-standard sweet potatoes available in the UK.

"Paris and London in particular were home to notable numbers of Japanese who took a taste for French gastronomy back to Japan"

The main thing is that I am slowly dry-roasting them, emulating the Japanese cooking method rather than boiling them—as is the case with most versions of British fish pie that uses them. This isn't just about "cultural congruence", it's also practical. Sweet potatoes contain quite a lot of water and that doesn't reduce when you boil them. By literally baking out some of the excess moisture before roughly mashing them to create a top layer, it reduces their tendency to become soggy when the fish pie is cooking in the oven.

If they bake down to being overly dry and crumbly, simply adding the little oil without a strong flavour—such as groundnut oil—and a few dashes of toasted sesame oil helps lubricate the mashing. It also helps to crisp up the top layer of panko when baked in the oven.

One thing I think important to mention is that I personally prefer the version of this recipe that uses half-and-half mashed sweet potato and daikon, because I don't have a sweet tooth. However, cooked daikon is a very particular flavour not to everyone's taste and thus I a doing the sweet potato version here.

A bit on the side

I'm doing the katsu fish pie here with two simplified versions of Japanese dishes as side dishes as well as an option for fusion dishes from the Japanese kitchen. Yep, lots of choice.

One is roasted baby leeks. The Japanese use leeks or, more accurately, Japanese leeks (naganegi) in numerous dishes ranging from hot pots and stir fries to soups or simply chargrilled, basted with marinade. The Japanese version are a bit like a hybrid of a leek and a large spring onion. You may be able to find them where you are in specialist grocers. But, if not, the closest thing is baby leeks which I am using here, roasted with a thin marinade and garnished with a furikake once cooked.

I'm also doing a simplified version of "smashed cucumber salad" (tataki kyuri) with a sesame dressing bought from a Japanese retailer rather than making it from scratch. It's ingredients are fairly complex, but if you do want to make your own, there are plenty of recipes out there. Similarly, I am using a fairly standard European cucumber but in Japan this salad is made with a number of different types of cucumber. Knock yourself out.

Similarly, I definitely recommend some tart or bitter Japanese pickles on the side to balance the sweetness of the sweet potato. In this instance I'm going for pickled "sushi" ginger (gari), sour cucumber (kyurizuke) and mustard leaf (takana).

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  Roasted baby leeks

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  Mixed bitter Japanese pickles

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  Smashed cucumber salad

Plan B

Since I knew that this katsu fish pie would produce a pie that meant that I would eat it more than once over a couple of days, I put together two other side dishes as alternatives. The focus for these two was more about considering fusion from a Japanese perspective. In other words, it might be said that both are Japanese side dishes that come out of the yōshoku trend for Western-influenced food.

One is a very simple dish of stir-fried green asparagus (yaki-asupara). Originally brought to Japan by Dutch traders in the 17th-century, asparagus was initially a commercial flop and only really started being adopted by sophisticates in the 1920s. Part of what accounted for this was that during the Taisho Period (1912-1926), increasing numbers of Japanese artists, intellectuals and scientists travelled to Europe or lived and worked there. Paris and London in particular were home to notable numbers of Japanese who took a taste for French gastronomy back to Japan. From the 1970s onwards it was eagerly adopted as a tasty foreign food by the broader population, complete with using butter to dress it.

The second is a dish that combines baby leeks (naganegi) with a sparing quantity of broad beans (soramame). Broad beans are traditionally cooked in numerous ways in Japan, but when stir-fried in more traditional Japanese cooking, they are usually part of a main dish—such as cooking them with prawns—rather than in this fusion side dish version.

Note: the Japanese tend to cook these dishes in a flat-bottomed pan rather than a wok, and these dishes need to me cooked on a medium heat not the high heat used in most wok cooking.

Again, I have selected these flavours as a kind of counterpoint to the sweet potato and will also serve them with bitter pickles.

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  Stir-fried baby leeks and broad beans with sesame seeds

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  `Stir-fried green asparagus with soy and butter

Take note:

I'm including pre-cooked carrots cut rather thickly in the Japanese style in this pie. The first time I cooked it without any vegetable content within the pie while developing the recipe, it was somehow a little too rich with only the fish, seafood and katsu curry-infused béchamel. This time I am using carrots because I am serving leeks as a side dish (see above). But, sautéd leeks or diced green bell peppers are wonderful alternatives as vegetable "spacers" and better options if you want to balance the sweetness of the sweet potato.

For this dish I recommend you use a deeper, narrower ovenproof dish than usually used to cook fish pie. Béchamel sauce has a tendency to bubble upwards during the baking process. Since sweet potato and panko are lighter than mashed potato they are less effective at keeping a tight "lid" on things. The extra depth creates extra space for movement without the sauce bursting over the edges.

This version is for 3 to 4 diners, depending on appetite and any side dishes.

I don't recommend freezing the already baked dish, but leftovers will keep well in the fridge for a couple of days.

While the cooking images were taken at the same time, there are images of serving it on two sequential occasions.

3 top tips to get this recipe right:

• It's important to assemble the contents of the pie and pour in the béchamel while it is still warm and fluid, gently folding it in so that it reaches right to the bottom of the dish. Once cool, store it in the fridge for a good few hours—I do it overnight. Not only do you want it fairly "solid" when you spread on the sweet potato topping, but also because béchamel has a tendency to bubble up in the oven. By ensuring it's at the bottom of the dish, you can prevent too much of it bubbling up above the crust.

• Don't worry about little flecks of the katsu curry sauce block remaining unintegrated into your béchamel—they are far less likely to melt completely when cooking at these reduced temperatures than in the boiling water for which they were designed. They will dissolve completely while baking in the oven or, better still, provide little nodes of intense flavour.

• I'm using a combination of cod, monkfish, smoked haddock, small scallops and prawns here. I'm using it as an opportunity to clean out the freezer, getting rid of remaining left over frozen fish from earlier experimental versions. But, you can use any combination of cooked fish and/or seafood you wish. My one caveat would be that you avoid notably oily fish such as mackerel, though salmon works well

Shopping list

for the katsu fish pie

• Approx. 450g of mixed cooked fish and seafood (see above)

• 3 or 4 carrots; peeled and cut into thick pieces

• 1 or 2 sweet potatoes

• panko breadcrumbs, enough to cover the surface of the pie

• 1tspn garlic & ginger paste

• 2tbspns unsalted butter

• 2tbspns of plain flour; sifted

• Approx. 500ml full-fat milk

• 1 portion katsu curry block (Japanese golden curry) - see above

• 1tbspn peanut oil (or other oil without a strong flavour)

• 1tspn toasted sesame oil

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  Steamed monkfish

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  Steamed small scallops

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  Steamed smoked haddock and cod

for the roasted baby leeks

• Approx. 2 baby leeks per diner; cut into fairly large pieces

• 2 tbsns yakitori sauce

• 1 tbspn rice wine vinegar; (or mirin)

• a little furikake for garnish (optional)

for the smashed cucumber salad

• Roughly 1 third of a cucumber per diner; washed and cut into large, irregular pieces, skin-on

• Japanese sesame dressing to taste

The Plan B side dishes

NB: the quantities of oil, soy sauce, etc. are for cooking these sides for 3 to 4 diners, but the images show me cooking them in portions for 1 to 2 diners, therefore slightly different.

for the stir-fried asparagus

• Approx. 70g fresh green asparagus (sprue) per diner; smaller rather than larger

• Approx. 1 tbspn rapeseed oil (canola oil) or rice-bran oil

• 1 large clove of garlic; peeled and bruised

• 1 tbspn light soy sauce

• 1 tbspn cold water

• Approx. 1 tbspn unsalted butter

for the stir-fried baby leeks and broad beans

• Approx. 2 baby leeks per diner, cut into fairly large pieces

• Approx. ¼ cup broad beans per diner; fresh or frozen, (but fully defrosted)

• Approx. 1 tbspn rapeseed oil (canola) or rice-bran oil

• 1 tbspn yakisoba sauce

• 1 tspn untoasted sesame seeds

• A dash of light soy sauce

Cooking Method

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the katsu fish pie

1. Cook the sweet potatoes. I am emulating the Japanese style of dry roasting them in their skins (scrubbed and pricked with a knife or fork) in a preheated oven for 60mins at 160°C. Once cooked, allow them to fully cool. (see above for more information if you would prefer to cook them another way)

2. Cook the carrots in a little salted water with 1tspn of garlic & ginger paste stirred in. When cooked, drain and place to one side

3. Cook all of your chosen fish and seafood by whatever method you prefer—I'm using a steamer, but it's equally fine to poach or use a microwave. All of the fish and seafood should be fully cooked, but still tender before placing into your ovenproof dish Place to the side and allow to fully cool

4. Once the fish and carrots are cooled, flake the fish into a fairly deep ovenproof dish, removing any bones or skin. Intersperse with pieces of carrot and cooked seafood. Season sparingly with a little salt as you construct your fish pie

5. Make a béchamel sauce by first melting the butter on a low-medium heat, adding the flour to create a roux and then adding the milk, about 100ml a time and constantly stirring until it becomes smooth, thick and bubbles a little before adding more milk and repeating this process. Once you have sufficient sauce in the pan (i.e. once you have used half of the milk), crumble in the kastu curry sauce block and stir in. Try to time adding it in the cycle when the sauce is thickening—and therefore hot—not when you are pouring in additional cold milk. This will mean that the curry sauce block will melt more easily. When you have a sufficient amount of suitably thickened sauce (i.e. using approx. 500ml milk) remove from the heat

6. While the béchamel is still warm and relatively fluid, pour over the fish and carrots. Gently turn over the ingredients in the ovenproof dish so that all ingredients are coated in the béchamel and as much of it as possible sinks to the bottom of the dish. Allow to cool fully and then place in the fridge for at least 3 hours (I usually do it the night before I want to serve the dish). This is because you want it to have set relatively firmly before covering with the sweet potato

7. When you are ready to bake your fish pie, mash the sweet potatoes, seasoning with a little salt. Add the peanut oil and sesame oil while mashing to produce a smooth mash

8. Cover the whole top surface of the chilled fish pie with the mashed sweet potato in an even, fairly thin layer. Sprinkle the panko breadcrumbs over the whole surface of the pie. You can spritz the panko with oil or even drop a few knobs of butter on top to deepen the crisping, but I don't: the oil in the sweet potato is enough to do this

9. Bake in an oven preheated to 180°C for 30min or until the panko crumbs are golden

10. Rest it briefly before plating or taking directly to table for diners to help themselves. Serve with your side dishes of choice

the roasted baby leeks

1. Place the leeks on a baking tray or in an ovenproof dish. Make the simple marinade by diluting a little yakitori sauce with a little rice wine vinegar. Thoroughly baste the leeks

2. I am roasting the leeks at the same time as the fish pie in the oven at 180°C for 20 to 30min (depending on how blackened you like them). Take out of the oven after 15mins, turn them and re-baste. Alternatively, if you would like to have a more authentic naganegi vibe, you can cook them under the grill, which will only take about 10mins

   When cooked, dress with a little furikake; plate or take to table in a serving dish

the smashed cucumber salad

1. Cut the cucumber into fairly large pieces and then "smash". You can either do this with a meat tenderiser or with the back of a heavy knife or cleaver. Prize apart the pieces where the cucumber naturally splits with clean hands and place into a serving dish, ensuring you pour over any cucumber juices from the chopping board

2. Dress with sesame dressing and take to table

The Plan B side dishes

the stir-fried asparagus

1. Cut the asparagus at steep, diagonally angles—this enhances how it absorbs flavours ,and that the surface and core cook more evenly. Rinse and pat dry with paper towels

2. Heat the oil in a frying pan with a lid on a medium heat. When hot, using tongs or chopsticks, hold the clove of garlic, rubbing it along the surface of the pan to subtly infuse the oil. When the aromas notably release, remove the garlic

3. Add the asparagus. Stir-fry, moving it about constantly. After a few minutes (3 or 4mins), when cooked but still a little al dente, rapidly add the cold water and cover the pan with the lid to flash-steam for 10 to 20secs

4. Uncover and push the asparagus to one side of the pan. Pour the soy into the other side of the pan (i.e. not over the asparagus). Wait until the soy "flashes up" and starts bubbling, then mix the asparagus into it

5. When the soy has been fully absorbed, remove from the heat. Add the butter and mix in, allowing it to be melted only by the residual heat of the pan. Cover and keep warm until serving

the stir-fried baby leeks and broad beans

1. Heat the oils in a frying pan on a medium heat, blending them together. When hot, add the baby leeks and stir-fry, moving almost constantly

2. When the outer layer of the baby leeks show signs of softening, add the broad beans and mix in. Stir-fry, moving almost constantly for about 3 to 4mins.

3. Add the sesame seeds, moving the ingredients constantly for a minute or two

4. When the sesame seeds are partially toasted, add the yakisoba sauce and stir in. Cook, stirring, for another minute or two. Once the yakisoba has cooked in, taste. Since yakisoba sauces vary, add a dash of soy (in lieu of salt) if needed

5. Remove from the heat. Cover and keep warm until serving

Alternatives

This is a pescatarian dish that also involves dairy used in ways (such as the roux) that do not work when using most non-dairy alternatives. Frankly, I would never attempt to create a vegan, vegetarian or carnivore version (except possibly with chicken or turkey) of this dish. It's one of those rare cases of "it is what it is" and I would look to other recipes if serving guests who cannot eat pescatarian dishes that include dairy.

Pairings

Japanese food is known to work with beer and I would really suggest going there with this one. The closer-to-bitter-than-sweet flavours of many beers have a great ability to cut through the sweet potatoes. On this occasion I had it with a classic Asahi Super Dry lager, which worked fabulously. On the whole I would suggest sticking to beer, sake or Japanese plum wine served on ice.

There will obviously be wines—white wines given the fish and seafood content—that work well with this dish, On the whole I have gone with my gut instinct and stuck with beer through the process of testing the recipe I am now putting out there.

Conventional wine wisdom often pairs up robust Gewürztraminers, Chenin Blancs or Riesling's from Alsace with katsu curry dishes. But this is not a normative katsu curry dish. The flavours are far more subtle. and overall, I think Albariño is the direction to go. To date Paco & Lola, Albariño from Galicia has offered both the best bang for buck of a white that really works with this dish. It's light and dry enough to not arm wrestle with the fish, but has enough acidity to keep the sweet potatoes in check.

Obviously it works with any number of alcohol-free drinks from ginger ale on ice to chilled sparkling water with a dash of yuzu juice.