Long slow cooking is unusual for fresh fish, but the mackerel do not dry out provided that they are kept covered with liquid and the dish has an intense, aromatic, oriental flavour.

1. Put the chillies, ginger, garlic, soy sauce, cider vinegar, sugar and about half the apple juice into a small pan. Bring to a simmer, stirring occasionally to dissolve the sugar, but taking care not to break the chillies.
2. Arrange the mackerel pieces in a heavy-based saucepan with few or no gaps between them. Pour over the sauce and add apple sauce if required to barely cover the fish, if necessary shaking the pan to re-blend the sauce and juice. Bring to a gentle simmer and turn down the heat.
3. Cook, covered, at a very gentle, popping simmer for 3 hours, topping up with a little more apple juice from time to time as required to keep the fish covered. Do not let it boil or move the fish at all.
4. Take the fish out of the cooking liquid, set aside and keep warm. Remove and discard the chillies.
5. Return the pan containing the cooking liquid to the heat, turn up the heat and boil until it is reduced by about a third to a half. Taste and adjust the seasoning to get a good balance of sweet, hot, salty and sour, adding more apple juice, vinegar, soy sauce or cayenne pepper as required.