01 - In a large mixing bowl, whisk together the Greek yogurt, olive oil, lemon juice, Dijon mustard, minced garlic, salt, and black pepper until smooth and well combined.
02 - Add the cooked chicken, celery, red bell pepper, red onion, parsley or dill, and optional nuts and grapes to the bowl with the dressing.
03 - Gently toss all ingredients together until everything is evenly coated with the dressing, taking care not to break apart the chicken pieces.
04 - Taste the salad and adjust the salt, pepper, or lemon juice as needed to suit your preference.
05 - Cover and refrigerate for at least 15 minutes to allow the flavors to meld together for the best results.
06 - Serve cold on its own, over a bed of fresh greens, in lettuce cups for a low-carb option, or as a sandwich filling on whole grain bread.