In a medium size pot, boil the penne pasta in salted water per the instructions on the box until al dente. Drain well.
Meanwhile, in a large mixing bowl, whisk together dry salad dressing mix, mayonnaise, milk, red wine vinegar, pesto, and olive oil. (May sweeten with 1 teaspoon sugar, if desired to balance flavor)
Add drained pasta to dressing mixing until fully coated.
To the pasta add, onion, green and red bell peppers, olives, Parmesan, mozzarella, pepperoni, salami, green onion and tomatoes. Mix until evenly distributed. Reserve some green onion for garnishing.
Taste and adjust salt and pepper to your taste. Place into an airtight container and chill for at least 4 hours. Stir before serving garnished with green onion.
Store leftovers chilled.