Boil the pasta: Bring a large pot of well-salted water to a boil and cook the rotini until just tender, about 9 minutes. Drain it and rinse under cold water to stop the cooking and prevent clumping.

Prep the vegetables: While the pasta cooks, dice the bell peppers, slice the red onion thin, and halve the cherry tomatoes and olives. Keep the pieces small and uniform so they mix evenly through the pasta.

Cube the salami and cheese: Cut the beef salami into small cubes about the size of the pasta pieces. Drain the mozzarella pearls if packed in liquid.

Combine in a large bowl: Add the drained pasta, salami, mozzarella, tomatoes, peppers, onion, and olives to a large mixing bowl. Toss gently to distribute everything evenly.

Add the dressing: Pour the Italian dressing over the salad along with the oregano, salt, and pepper. Toss until every piece of pasta and vegetable is coated and glossy.

Chill the salad: Cover the bowl and refrigerate for at least 1 hour, or overnight, so the pasta absorbs the dressing and the flavors settle together.

Taste and adjust: Pull the salad from the fridge and taste it, since cold temperatures mute flavor. Stir in extra dressing, salt, or a squeeze of lemon if it tastes flat.

Finish and serve: Sprinkle the chopped parsley over the top just before serving for a fresh, green finish. Serve the salad cold or at room temperature.