Step 1: In a large mixing bowl, combine the cooked chicken, celery, red onion, grapes, and nuts. Mix well to evenly distribute the ingredients.
Step 2: In a separate small bowl, whisk together Greek yogurt (or sour cream), Dijon mustard, lemon juice, salt, and pepper until well combined. Taste and adjust the seasoning if needed.
Step 3: Pour the dressing over the chicken mixture and toss gently to coat all the ingredients with the dressing.
Step 4: If desired, serve the chicken salad on a bed of lettuce or salad greens. You can also make sandwiches by spooning the chicken salad onto some nice turkish bread. Tip: Feel free to customise the recipe by adding other ingredients like diced apples, dried cranberries, or fresh herbs like parsley or dill.