Mix the Greek yogurt and Dijon mustard in a bowl until the mixture is smooth.
Add the cooked chicken, celery, and diced apple to the yogurt mixture.
Stir all ingredients together until they are well combined. Season with salt and pepper to taste.
Cover the bowl and chill the chicken salad for 1 hour before you serve it.
Notes
Serve this salad on lettuce leaves or toasted bread. Garnish with fresh herbs before serving. This recipe is by Grace Williams, contributor at Recipes by Betty.