Cook tri-color rotini pasta according to package directions, then drain and rinse with cold water until cooled. This stops the pasta from continuing to cook.

Combine tri-color rotini pasta, salami, pepperoni, mozzarella cheese, cherry tomatoes, cucumber, black olives, green bell pepper, and red onion in a large bowl. Mix to distribute the colorful vegetables and meats evenly.

Add Italian dressing, Parmesan cheese, and Italian seasoning, then toss until every piece is coated. The pasta should look glossy and the cheese should cling to the noodles.

Season with salt and pepper. Taste and adjust so the dressing flavor is balanced.

Refrigerate for at least 2 hours, tossing occasionally. Keep it covered so the surface stays moist and the flavors meld.

Before serving, check the texture and add more Italian dressing if needed, then toss again. Serve cold so the ingredients stay crisp.