1 medium onion, thinly sliced
2 garlic cloves, chopped
2 large tomatoes, chopped
1 medium eggplant, cut into 1-inch dice
1 medium zucchini, sliced crosswise 1-inch thick
10 ounces cremini or other mushrooms, sliced
1 medium red pepper, cut into 1-inch pieces
1 teaspoon oregano
1 teaspoon basil
1 tablespoon balsamic vinegar