- In a large bowl, combine the cooked chicken, red grapes, celery, walnuts, and green onions. 
- In a separate small bowl, whisk together the mayonnaise, Dijon mustard, apple cider vinegar, honey, salt, and pepper until smooth. 
- Pour the dressing over the chicken mixture and gently toss until everything is well coated. 
- Taste and adjust seasoning if necessary. 
- Cover the bowl and refrigerate for at least 30 minutes to allow the flavors to meld. 
- Serve the chicken salad on a bed of lettuce leaves or as a sandwich filling.