Baked mackerel with tangy tomato, red onion & basil

Preheat the oven to 200ºC, gas mark 6. Brush the base of a small roasting tin with a dash of the oil. Place the fish side by side in the tin, skin-sides down, and bake for 10 minutes.

Reserve plenty of the smaller basil leaves and tear the rest into pieces, discarding the stalks. Halve the tomatoes. Using a teaspoon, scoop the pulp into a sieve set over a bowl to catch the juice. Use the back of the teaspoon to press as much juice as you can out of the tomato pulp. Slice the tomato flesh.

Heat the remaining oil in a saucepan and fry the onion for 1 minute. Stir in the tomato juice, tomatoes, torn basil, sugar, vinegar, tomato paste, 4 tbsp water and a little black pepper. Heat through for 1 minute, or until the basil has wilted. Move the mackerel to plates, top with the tomato and onion mixture and serve scattered with the reserved basil leaves.