Shallow fry 10 x 150 g mackerel steaks in olive oil, then transfer to an earthenware dish. Sweat 75 g chopped onion and 2 chopped cloves of garlic in oil, add 75 g carrots, cut into small dice, 1 bayleaf, 10 crushed peppercorns, chopped parsley and oregano, 2 tsp chilli powder, 225 ml dry sherry or wine vinegar and 125 ml water.

Simmer for 5 minutes then pour over the fish, cover with clingfilm and marinate for 24 hours.