In a medium saucepan, melt the margarine. Add the zucchini, onion, pepper and carrot and sauté until the onion is tender, about 4 -5 minutes. Stir in the flour, cook and stir for 1 minute. Gradually stir in the milk, cook and stir until the mixture boils and thickened. Blend in the Cheddar cheese and black pepper, heat and stir until the cheese melts. Serve hot. Makes 4 servings.