In a large mixing bowl, combine the cooked chicken, diced apple, dried cranberries, diced celery, and red onion.
In a separate small bowl, whisk together the mayonnaise and fresh lemon juice until smooth.
Pour the dressing over the chicken mixture and stir until everything is well coated.
Add salt and pepper to taste, adjusting seasoning as desired.
If using nuts, fold them in gently to avoid breaking them.
Chill the salad in the refrigerator for about 30 minutes to allow the flavors to meld.
Serve the salad on a bed of greens or enjoy it in a sandwich, as desired.