• 4 thick cod steaks
• milk for soaking
• 225 g shallots or small onions
• 3 large cloves garlic
• 2 fresh red chillies
• 500 g ripe tomatoes (plum variety if available)
• 3 tablespoons olive oil
• 1 level tablespoon tomato purée
• grated rind and juice of 2 limes
• 1 teaspoon caster sugar
• 1 large avocado
• lemon juice for sprinkling
• sea salt

Put the fish steaks into a dish in which they fit fairly snugly and pour on enough milk to cover. Cover the dish with cling film and leave in the fridge for at least 2 hours. Lift out the fish and pat dry with kitchen paper. Discard the milk.

Peel the shallots and slice across thinly. Peel the garlic and chop finely. Cut open the chillies under running water, discard the seeds and stem and then slice the chillies across finely.

Pierce the tomatoes, place in a bowl and pour boiling water over them. Leave for a few minutes, then take out, peel and chop finely.

Heat the olive oil in a wide, heavy-based flameproof casserole over a medium heat. Add the shallots and stir for a few minutes until soft and golden. Add the garlic and chillies and stir for another minute.

Now add the chopped tomatoes with their juice, tomato purée, lime rind and juice, sugar and a sprinkling of sea salt. Put the lid on the casserole and bubble gently, stirring now and then, for about 10 minutes until the tomatoes are pulpy and form a thick sauce.

Place the fish steaks on top of the sauce, re-cover and cook over a low heat for 10-15 minutes or until the fish is opaque and feels just about firm when lightly pressed.

Meanwhile, halve the avocado and remove the stone, then carefully peel off the skin. Slice the avocado flesh across thinly into half-moon shapes and sprinkle with lemon juice.

When the fish is cooked, remove the casserole from the heat. Scatter the avocado slices over the fish steaks and serve as soon as possible.