1. Preheat the oven to 160°C.
2. Have the fish cleaned, leaving the head and tail on. Prick the fish on both sides with a coarse-tined fork, rub in the sea salt and lime juice, and set aside in an ovenproof dish to season for about 2 hours.
3. Heat 65ml olive oil in a heavy-bottomed frying pan and fry the onion and garlic, without browning, until they are soft. Add the tomatoes, with the rest of the ingredients, to the pan and cook the sauce over a brisk heat until it is well seasoned and some of the juice has evaporated - about 10 minutes. Pour the sauce over the fish.
4. Sprinkle the remaining 3 tablespoons olive oil over the sauce and bake the fish for about 20 minutes, loosely covered, on one side. Turn the fish over very carefully and continue baking it until it is just tender - about 20 minutes. Baste the fish frequently with the sauce during the cooking time.

Reproduced with kind permission of Diana Kennedy from "The Essentials of Mexico", which is published by Clarkson Potter/Publishers