Heat the oil in a large skillet and saute the onion, bell pepper, and garlic for 3 to 4 minutes.
1 tbsps olive oil, 1 cup onion, 2/3 cup mixed bell peppers, 1 clove garlic
Add all remaining ingredients except the Parmesan cheese, cover, and cook over medium heat, stirring occasionally, for about 10 minutes or until vegetables are tender-crisp.