Heat the olive oil in a large skillet over medium-high heat. Add the red and yellow bell peppers, mushrooms, zucchini, onion and garlic, and stir to cook evenly. Season with steak seasoning and onion powder. Cover, and cook for about 10 minutes.
Add the sausage to the skillet, and cook, stirring occasionally, for another 10 minutes. Just before serving, add a splash of balsamic vinegar, and sprinkle liberally with Parmesan cheese.
