Heat oven to 350ºF. In 12-inch nonstick skillet, cook beef and onion over medium heat 8 to 10 minutes, stirring occasionally, until thoroughly cooked; drain well. Stir in frozen vegetables, mushrooms, tomatoes, gravy, chili sauce, basil and pepper. Heat to boiling. Reduce heat; cover and simmer about 10 minutes or until vegetables are tender.