While bringing water to a boil for the pasta, dice the red onions finely and set aside. Seed and dice the roma tomatoes into 1/2-inch pieces, then slice the pepperoncini peppers and black olives. Grate the parmesan cheese fresh if you haven't already—freshly grated cheese has better texture and absorbs the dressing more effectively than pre-shredded. Once water is boiling, cook the rotini according to package directions until al dente, then drain and rinse thoroughly with cold water until completely cooled. This stops the cooking process and prevents the pasta from becoming mushy when mixed with the dressing.

In a large bowl, combine the cooled pasta from Step 1 with the diced red onions, tomatoes, pepperoncini peppers, grated parmesan cheese, and black olives. Pour in the Italian dressing and sprinkle the dried oregano over top. Toss everything together thoroughly, making sure the dressing coats all the pasta and vegetables evenly. I like to use Olive Garden Signature Italian dressing—it has the perfect balance of vinegar and herbs that makes this salad authentic.

Top the dressed pasta mixture with the romaine lettuce, but don't toss it in yet—keeping it on top prevents the lettuce from wilting during chilling. Cover the bowl and refrigerate for at least 1 hour so the flavors meld and the salad becomes properly chilled. Just before serving, stir everything together well to distribute the lettuce throughout. This final toss ensures every bite has a mix of pasta, vegetables, cheese, and fresh lettuce.