Cook tortellini according to packet directions until al dente.
While tortellini is cooking prepare marinade. Combine vinegar, mustard, garlic, basil, chopped parsley, onions and salt and pepper to taste.
Drain tortellini and rinse in cold water. Pour marinade over tortellini, add olives (and optional ingredients, see above) and refrigerate. When ready to serve add Parmesan and some fresh parsley for garnish, if desired. Serve with toothpicks.