Bring a large stockpot of salted water to a rolling boil. Add the rotini and cook according to package directions until al dente, about 9 to 11 minutes.
Drain the pasta in a colander and rinse briefly under cold water to stop the cooking. Let it sit for a few minutes, shaking occasionally, so excess water drains off.
While the pasta cooks, cube the Genoa salami into pieces roughly the same size as the mozzarella pearls. Halve the cherry tomatoes, and slice the olives, pepperoncini, and red onion thinly. Dice the red bell pepper into small, even pieces.
Add the drained, slightly cooled pasta to a large mixing bowl. Pour in the zesty Italian dressing along with the tablespoon of pepperoncini brine and toss thoroughly so every piece of pasta is coated.
Add the cubed salami, mozzarella pearls, cherry tomatoes, black olives, red onion, bell pepper, and pepperoncini to the bowl. Toss gently to combine, ensuring the dressing reaches the vegetables as well as the pasta.
Sprinkle the grated parmesan cheese and chopped parsley over the top. Fold everything together one more time until the parmesan is evenly distributed. Season with salt and black pepper to taste, keeping in mind the salami and parmesan are already salty.
Serve right away, or cover and refrigerate for at least 30 minutes for the flavors to meld. Give it one more toss just before serving, as the dressing tends to settle at the bottom.