Mix mayonnaise, sour cream, lemon juice, salt, and pepper to make the sauce.
Combine shredded chicken, halved red grapes, chopped pecans, and chopped celery in a bowl.
Add the sauce and optional chopped sweet onion to the bowl and toss to coat.
Serve the chicken salad with lettuce leaves, whole wheat bread slices, or store leftovers in the refrigerator.
