Prepare the Dressing: In a medium-sized bowl or liquid measuring cup, combine 1/2 cup mayonnaise, 1/4 cup grated parmesan, 3 tablespoons of red wine vinegar, 1-2 tablespoons of banana pepper juice, 1 teaspoon of oregano, and 1 teaspoon of garlic powder. Season with freshly cracked pepper and 1/4 teaspoon of salt. Mix until smooth and well combined. Taste and adjust seasoning as necessary.
Combine the Salad Ingredients: In a large mixing bowl, add 2 cups of shredded rotisserie chicken, 1/4 lb. diced salami or soppressata, 1/4 lb. diced pepperoni, 1/4 cup diced provolone cheese, 1/4 cup crumbled feta cheese, 2/3 cup diced grape tomatoes, 1/3 cup mild banana peppers, and 1/2 sliced or diced red onion. Gently toss the ingredients together to ensure an even distribution of flavors and textures.
Dress the Salad: Pour about 3/4 of the prepared dressing over the bowl of salad toppings. Toss everything together well to coat all of the ingredients evenly. Taste the salad and add more dressing if desired.
Store and Serve: Transfer the completed salad into an airtight container and store it in the refrigerator. The salad can be kept for up to 4 days. When ready to serve, enjoy it with fresh vegetables, crackers, or tortilla chips, or consider using it as a filling for sandwiches.
Leftover Dressing: If you have any dressing left after preparing the salad, store it in a sealed container in the refrigerator. You can add the leftover dressing to the chicken salad the next day if needed, as it may absorb some of the flavors as it sits.