1. In a large saucepan, saute onion in oil until tender. Add garlic; cook 1 minute longer. Add the tomatoes, zucchini, carrots, peppers, water, salt and pepper. Bring to a boil.
2. Reduce heat; cover and simmer for 20-25 minutes or until vegetables are tender, stirring occasionally. Stir in mushrooms; cook 10 minutes longer or just until mushrooms are tender.
3. Serve over pasta. Sprinkle with cheese. Yield: 6 cups.