Heat the oven to 200oC (400oF), Gas 6. Heat the oil in an ovenproof casserole and fry the onion over moderate heat for about 3 minutes. Add the carrots and celery, stir and cook for 2 minutes. Add the mushrooms and tomatoes, season with salt and pepper and stir in the lemon juice. Cut the fish into large chunks and carefully stir into the casserole. Cut the bread into triangles and arrange over the casserole 'buttered' side up. Bake for 15-20 minutes, until the topping is crisp.
A green vegetable such as broccoli or spinach.
Per Serving : 330 calories, 12 g fat, 7 g fiber.