Aji fish sits in that useful middle ground between delicate white fish and richer oily fish. It is a type of horse mackerel with a clean, slightly sweet flavour, and it can anchor everything from crisp fried cutlets to a simple grilled dinner. In this article, I focus on the main dishes that make it shine, the cooking methods that work best, and the small buying and prep decisions that matter in a UK kitchen.
The quickest way to cook horse mackerel well is to keep the seasoning simple and the finish crisp
- Horse mackerel has enough fat to stay juicy, but it still benefits from a light hand with sauces and spices.
- Aji fry is the most forgiving main dish for home cooks because panko and hot oil hide small filleting imperfections.
- Grilled and vinegar-marinated versions are better when you want a lighter meal or a make-ahead dinner.
- In the UK, specialist Japanese grocers and fish counters are usually the easiest places to find it.
- Aji pairs well with rice, cabbage, citrus, ginger, daikon, and other sharp or fresh flavours.
Why horse mackerel earns a place on the main course
Despite the common English name, this fish is not the same as the blue, strongly flavoured mackerel many British cooks know. It is firmer, cleaner, and often a little sweeter, which makes it unusually versatile. I like it because it can take a little heat without falling apart, but it still tastes refined enough to serve with very few ingredients.
That balance is what makes it so useful in Japanese home cooking. You can fry it, grill it, marinate it, or mince it with herbs and miso, and it still feels like a proper main dish rather than a side note. Once the fish makes sense on the plate, the next question is which preparation gives the best return for the least effort.
The main dish styles I would reach for first
| Dish | Texture | Effort | Best use | Why I like it |
|---|---|---|---|---|
| Aji fry | Crisp outside, juicy inside | Moderate | Family dinner, bento, comfort food | The most forgiving way to learn the fish |
| Shioyaki | Clean, smoky, lightly salty | Low | Light dinner or set meal | Best when the fish is very fresh |
| Nanbanzuke | Sweet-sour and tender | Moderate | Make-ahead lunch or summer meal | Works well with vegetables and holds flavour after chilling |
| Namero | Rich, savoury, aromatic | Moderate | Rice bowl, starter, or light main | Good for smaller fish or trimmings |
If I had to rank them for a UK home kitchen, I would start with aji fry, then shioyaki, then nanbanzuke. That order is about reliability, not tradition. All three work, but they ask different things from the fish and from the cook, and the easiest way to understand that is to begin with the version that forgives small mistakes.
Why aji fry is the most forgiving place to start
Aji fry is the dish I would recommend first to anyone who wants a clear result without a lot of drama. The fish is usually butterflied from the back, a method known as sebiraki, which opens the fish neatly and gives you a flatter piece that fries evenly. Once it is seasoned, floured, dipped, and coated in panko, the coating does most of the work.
The rhythm is simple. Pat the fish dry, season it lightly with salt, dust it with flour, then egg, then panko. Fry at around 170 to 180°C until the coating is golden and the flesh flakes easily, usually in about 6 to 8 minutes total depending on thickness. Drain it on a rack rather than paper if you want the crust to stay crisp.
- Do not fry wet fish. Moisture is the fastest way to get a soggy crust.
- Do not crowd the pan. Oil temperature drops quickly, and the coating drinks up grease.
- Do not drown it in sauce. Aji fry wants contrast, not a heavy glaze.
- Serve it with shredded cabbage, lemon, and a tangy sauce if you want the classic balance.
This is also the version that makes the most sense for bento, because the flavour stays good even after it cools a little. If you want the clearest learning experience, a fried version is the easiest starting point, and then you can move to the more restrained styles.
Grilling and marinating give you two very different dinners
Salt-grilled fish for the cleanest flavour
Shioyaki is the simplest way to taste the fish itself. I lightly salt the fish, let it sit for about 10 minutes, wipe away surface moisture, and then grill it under a hot grill or in a pan until the skin crisps and the flesh just turns opaque. It is the version I use when the fish looks fresh enough that I do not want to hide anything.
Serve it with grated daikon, lemon, rice, and maybe a small bowl of miso soup. The whole point is restraint. If the fish is clean and well handled, you will not need much more than salt and heat.
Read Also: Perfect Salted Salmon - Your Easy Shiozake Recipe
Nanbanzuke for a sharper, make-ahead meal
Nanbanzuke is a vinegar-based marinade that turns fried or pan-fried fish into something brighter and more layered. The fish is usually dusted, cooked until crisp, then dressed in a sweet-sour mixture with soy, vinegar, mirin, and thinly sliced vegetables such as onion or carrot. It is the dish I reach for when I want lunch to taste even better after a short rest in the fridge.
I prefer this style in warm weather, or whenever I want to make one batch and eat it twice. The acid lifts the fish, the vegetables add texture, and the whole dish feels lighter than it really is. If you want a different texture and mood, grilling or marinating shows how flexible the fish really is.
How to buy and store it in the UK without ruining the texture
In the UK, I would start with Japanese supermarkets, specialist fish counters, or online Asian grocers rather than a standard supermarket shelf. Stores such as Oriental Mart or Atariya are the kind of places that are more likely to carry horse mackerel or be able to source it. If you only find frozen fillets, that is still useful. For a first attempt at aji fry or grilled fish, frozen can be perfectly practical.
| What to look for | Good sign | Why it matters |
|---|---|---|
| Eyes | Clear and bright | Usually a sign of fresher whole fish |
| Skin | Shiny and tight | Suggests the fish has not dried out |
| Flesh | Firm, springs back when pressed | Better texture after cooking |
| Smell | Clean and marine | Strong ammonia or metallic notes are a warning sign |
| Frozen pack | Tight seal, no freezer burn | Helps preserve flavour and moisture |
For fresh fish, I try to cook it within 24 hours if possible, and I keep it in the coldest part of the fridge. For frozen fish, I thaw it overnight in the fridge and cook it the same day. Whole fish are better for grilling and traditional frying, while fillets make the first attempt much easier. The last piece is choosing the plate around the fish so the meal feels complete rather than busy.
The plate I would build around it in a UK kitchen
When I want the fish to stay the star, I keep the rest of the plate tight and practical. Aji fry works best with steamed rice, shredded cabbage, and a sharp sauce. Shioyaki needs less: rice, grated daikon, a green vegetable, and something salty or citrusy on the side. Nanbanzuke can carry more vegetables and still feel balanced, so it pairs well with cucumber salad or a simple bowl of soup.
- For aji fry, I use rice, cabbage, lemon, and Worcestershire-style or tartar sauce.
- For shioyaki, I use rice, miso soup, grated daikon, and pickles.
- For nanbanzuke, I use rice, cucumber salad, and a light soup or tea.
As a rough guide, I aim for about 120 to 150 g of cleaned fish per adult for a main course, or around 80 to 100 g if I am building a bento-style lunch with several side dishes. For me, the best first cook is still aji fry, because it shows the fish’s sweetness and gives you a clear benchmark for later recipes. Once that works, you can move to salt grilling for purity and nanbanzuke for a sharper, more composed meal.
