To make the dressing, in a large bowl whisk together the olive oil, balsamic vinegar, Dijon mustard, and salt and pepper to taste (I like 1/2 teaspoon salt and 1/4 teaspoon pepper).
To make the pasta salad:
In a large pot, bring 4 quarts of water and 1 tablespoon salt to a boil. Add pasta and cook until tender, about 8 to 10 minutes. Drain well, rinse with cold water, and drain again.
To the bowl with the dressing, add the cooled pasta, celery, roasted red peppers, mozzarella, salami, pepperoncini, and capers. Toss to combine and sprinkle with fresh parsley.
Celery. Celery is crucial. It's light, refreshing, crunchy, and not salty. It helps balance out all the other soft, salty ingredients like, mozzarella, salami, roasted red peppers, capers, and pepperoncini.
Mozzarella: Chopped into bite-sized pieces (or use mini mozzarella balls or pearls).
Pepperoncini peppers: I buy the sliced ones for this salad. If you want to help your friends or family avoid them, substitute whole pepperoncini and use them as a garnish.
Yield: This recipe makes 12 (1-cup) servings.
Storage: Store leftovers covered in the refrigerator for up to 4 days.
Make ahead: The balsamic vinaigrette can be made up to 3 days in advance. Store covered in the refrigerator. The pasta can be cooked, drained, rinsed, and cooled up to 1 day in advance. The vegetables can be prepped the day before and stored separately in the refrigerator.
More mix-ins: Get creative with diced bell peppers, olives, fresh basil, a handful of toasted walnuts or almonds, or fresh mushrooms. Just be wary of adding too many soft, salty ingredients. Salami, mozzarella, roasted red peppers, capers, and pepperoncini are all soft and salty. You want balance!
Make the vinaigrette your own: Try adding 1 tablespoon fresh lemon juice, a teaspoon of honey, a minced clove of garlic, or a pinch of red pepper flakes.