In a medium bowl, whisk together Greek yogurt, olive oil, red wine vinegar, and pepperoncini brine until smooth, then add Dijon mustard, grated garlic, oregano, and red pepper flakes. Season with salt.

In a large mixing bowl, combine garbanzo beans, white beans, turkey breast, salami, green bell pepper, cherry tomatoes, sliced pepperoncini, red onion, parsley, and cheese. Toss to combine.

Pour the dressing over the mixed salad, toss gently until everything is evenly coated.

Cover and refrigerate for at least 30 minutes before serving. Toss again and garnish with extra pepperoncini if desired.