1 pound thin spaghetti
1 (8 ounce) bottle Italian salad dressing
1/4 cup red wine vinegar
1 small red onion, chopped
1 (8 ounce) package pepperoni sausage, chopped
1 (4 ounce) jar sliced mushrooms
1 (16 ounce) can Italian-style diced tomatoes, drained
1 (3 ounce) jar sliced green olives, drained
1/4 (2.62 ounce) bottle salad seasoning mix
2 cups shredded Parmesan cheese
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.