Put the mullets in a large shallow bowl and pour over the lemon juice. Set aside at room temperature for 15 minutes.

Preheat the oven to moderate 180°C (Gas Mark 4, 350°F).

Combine the pine nuts, garlic, onion, parsley and seasoning and gradually beat in the oil until the mixture is smooth and blended. Set aside.

Remove the fish from the marinade, discarding the marinating liquid and pat dry with kitchen towels. Arrange the fish, in one layer, in a large baking dish. Spread over the pine nut mixture making sure that each fish is evenly covered. Arrange the pepper strips over the fish and cover with the tomatoes. Dot over the butter and place the dish in the oven. Bake for 25 minutes, or until the fish flesh flakes easily.

Remove the dish from the oven and transfer the fish to a warmed serving dish. Place the olives in the uppermost eye socket of each fish and serve at once.