In a Dutch oven, saute the onions and peppers in oil until tender. Add garlic; cook 1 minute longer. Add the zucchini, summer squash, tomatoes, eggplant and mushrooms; cook and stir for 5 minutes., Stir in the remaining ingredients. Bring to a boil. Reduce heat; simmer, uncovered, for 1-1/2 to 2 hours or until sauce is thickened.