Bring a large pot of lightly salted water to a boil. Add pasta and cook for 8 to 10 minutes or until al dente; drain and place in a serving bowl.
Pour the salad dressing and vinegar over the noodles, and mix well. Add the onion, pepperoni, mushrooms, tomatoes, olives, seasoning mix, and parmesan cheese and stir until well combined. Serve at room temperature, or cover and refrigerate for several hours, or overnight.