In a large skillet over medium heat, brown sausage; drain. Add onion and mushrooms; saute until onion is tender. Add rice, consomme, water and oregano; mix well. Transfer to an ungreased 13-in. x 9-in. baking dish. Cover and bake at 350° for 55-60 minutes or until rice is tender, stirring once. Sprinkle with Parmesan cheese if desired. Yield: 8 servings.