Summer Minestrone

Heat the oil in a large heavy-bottomed saucepan over medium heat. Add the onion, season with 1/2 teaspoon each salt and pepper and cook, covered, stirring occasionally, for 5 minutes. Uncover and cook, stirring occasionally, until the onions are tender and beginning to brown, 4 to 5 minutes more. Meanwhile, separate the basil leaves from the stems. Finely chop enough stems to yield 1 tablespoon. Add the chopped stems to the onion along with the garlic and cook, stirring, for 1 minute. Add the potatoes and broth and simmer for 5 minutes. Add the zucchini, squash, and carrot and simmer for 3 minutes. Add the peas and corn and simmer until the vegetables are just tender, 2 to 3 minutes more. Sprinkle with the Parmesan and basil before serving. Serve with the bread, if desired.