1 Lightly coat the grill with cooking spray and preheat for 5 minutes.
2 Place the chicken on the grill and cook for 5-7 minutes.
3 Cut into small cubes when cool.
4 In a large bowl, add chicken, grapes, celery, onion and walnuts.
5 In another bowl, mix together the mayonnaise, mustard, salt, pepper and juice to make a dressing.
6 Drizzle the mixture over the chicken salad and gently toss.