In a medium bowl, whisk together the extra virgin olive oil, red wine vinegar, and fresh lemon juice. Add the dried parsley, dried onion, dried basil, dried oregano, garlic salt, granulated sugar, freshly cracked black pepper, dry mustard powder, and crushed red pepper flakes. Whisk until well combined and the sugar is dissolved. Set the dressing aside—I like to make this first so the flavors can start melding together while I prepare the other components.
Bring a large pot of salted water to a boil and cook the rotini pasta according to package directions until al dente. Drain the pasta in a colander, then rinse it thoroughly with cold water for about 1 minute, stirring occasionally, to stop the cooking process and cool it down completely. This prevents the pasta from becoming mushy and allows it to absorb the dressing properly.
While the pasta cooks, prep all your solid ingredients: quarter the genoa salami slices, halve the cherry tomatoes, finely dice the red onion, and chop the fresh flat-leaf parsley. Measure out the mozzarella pearls, sliced olives, and pepperoncinis. Having everything ready before mixing ensures the salad comes together quickly and evenly.
Place the cooled pasta in a large mixing bowl and pour half of the vinaigrette dressing from Step 1 over it. Toss well to coat the pasta evenly, ensuring the dressing penetrates throughout. This initial coating allows the pasta to absorb flavor from the dressing before the other ingredients are added.
Add all the prepped ingredients from Step 3 to the dressed pasta: the salami, mozzarella, olives, red onion, cherry tomatoes, pepperoncinis, and fresh parsley. Pour the remaining dressing over the mixture and toss gently but thoroughly until everything is well coated. Finish by sprinkling the freshly grated parmesan cheese over the top and folding it in gently—I keep some of the parmesan separate to sprinkle just before serving so it stays fresh and doesn't get soggy.
Transfer the pasta salad to a serving bowl or storage container and refrigerate for at least 1 hour before serving. This resting time allows all the flavors to meld together beautifully. Give it a gentle stir before serving, and add a bit more fresh parmesan if desired.