In a small bowl, combine the Hidden Valley(R) Original Ranch(R) Dressing and mustard and stir until well blended.
In a large bowl, add the diced chicken, grapes, celery, pecans, and green onion. Add the dressing to the salad and toss until evenly coated. Chill covered for 2 hours before serving.
The chicken salad can be served over a bed of lettuce, spinach, in a wrap or between slices of bread.