Place the pecans in a dry skillet over medium/low heat and toast for 3-5 minutes - stirring frequently until golden brown. Transfer to a cutting board and coarsely chop.
In a lage mixing bowl, combine diced chicken, halved grapes, sliced celery, chopped onion and cooled pecans.
In a small bowl, add all o the dressing ingredients and stir to combine.
Add all of the dressing to the salad, and stir until salad is evenly coated with dressing. Refrigerate.