Toast the pecans in a dry skillet over medium heat for 3-4 minutes until fragrant. Set aside to cool.
In a small bowl, whisk together mayonnaise, sour cream, sugar, apple cider vinegar, salt, pepper, and optional garlic and onion powders until smooth.
In a large bowl, combine the cooked chicken, diced celery, halved grapes, and toasted pecans.
Pour the dressing over the chicken mixture and stir gently until everything is evenly coated.
Taste and adjust seasoning with more salt or pepper if needed.
Cover and refrigerate for at least 30 minutes before serving to allow flavors to meld.
Serve chilled on bread, in lettuce wraps, or with crackers.
