Heat oil in a medium saucepan over medium heat. Add bell peppers, onion, crushed red pepper, and garlic to pan. Cook 15 minutes or until peppers are tender, stirring occasionally. Stir in tomato and salt. Cover, reduce heat, and cook 30 minutes, stirring occasionally. Stir in vinegar. Increase heat, and cook, uncovered, 5 minutes or until the liquid almost evaporates. Sprinkle with basil.