Preheat oven to 375°F. Arrange fish fillets in an oiled baking dish. Arrange tomato and cucumber slices over each fillet. Heat oil in a heavy saucepan over medium heat. Saut, onion, garlic and bell pepper until onion is tender. Do not brown. Remove from heat. Stir in remaining ingredients. Spoon mixture over fillets. Bake 20 minutes or until fish flakes easily.
