As a variation, other vegetables such as zucchini, eggplant or mushrooms, can be added to the peppers. The fish may be served hot or at room temperature.
Trim, scale and gut the fish. Rinse and dry it, then score both sides. Heat the oven to 350°F/175°C.
In a large flameproof baking dish or roasting pan, heat 2tablespoons of the oil and fry the onions until browned. Stir in the peppers, tomatoes, olives, anchovy fil