Cook the boneless, skinless chicken breasts by grilling, baking, or pan-searing until fully cooked. Allow to cool slightly, then cut into cubes.
Chop the celery and red onion, ensuring the celery is sliced thinly for crunch and the onion is finely chopped.
Quarter the red seedless grapes to add sweetness to the salad.
In a large mixing bowl, combine the non-fat Greek yogurt, garlic powder, black pepper, and a pinch of sea salt. Stir until well combined.
Add the cubed chicken, chopped celery, red onion, and quartered grapes to the bowl with the yogurt dressing. Gently fold until well coated.
Serve the salad in halved whole-wheat pita pockets or on a bed of romaine lettuce.
