saute' white onions, green bell peppers, red bell peppers, yellow bell peppers, mushrooms, in a little olive oil & butter. While this is cooking, place Italian Sausage on pan or grill or smoker while turning occasionally. After browning on all sides, place sausage in bun and garnish with your sauteed ingredients & topped with mozzarella cheese. Place on cooking pan and put in oven to broil for only a few minutes and please watch closely for over browning, it will burn.