Place fish in glass baking dish. Pour lemon juice over. Season with salt and pepper. Chill while preparing sauce. Blanch tomatoes in pot of boiling water for 20 seconds. Drain. Peel tomatoes. Cut tomatoes in half; squeeze out seeds. Chop tomatoes; set aside. Heat oil in heavy large skillet over medium heat. Add onions, cover and cook until soft and golden brown, stirring occasionally, about 20 minutes. Add garlic and saute 30 seconds. Mix in cumin, then tomatoes. Simmer sauce 5 minutes. Add fish with lemon juice and simmer until fish is just cooked through, about 10 minutes. Using slotted spatula, transfer fish to platter. Boil sauce in skillet until slightly thickened, about 5 minutes. Season to taste with salt and pepper. Spoon sauce over fish. Serves 4. Bon Appetit May 1995 Per serving: 576 Calories (kcal); 43g Total Fat; (63% calories from fat); 8g Protein; 49g Carbohydrate; 0mg Cholesterol; 51mg Sodium Food Exchanges: 0 Grain(Starch); 0 Lean Meat; 8 Vegetable; 1/2 Fruit; 8 1/2 Fat; 0 Other Carbohydrates Converted by MM_Buster v2.0n.