Start with 2 cups of cooked, shredded chicken. Use leftover roasted chicken or poach chicken breasts until tender and shred them using two forks.
Halve 1 cup of red seedless grapes, chop 1/2 cup of celery, and finely slice 1/4 cup of green onions.
In a bowl, combine 1/2 cup Greek yogurt and 1/4 cup mayonnaise. Stir in 2 tablespoons poppy seeds, 1 tablespoon lemon juice, and season with salt and pepper to taste. Mix well until smooth.
Add the shredded chicken, grapes, celery, and green onions to the dressing. Gently fold everything together so the dressing coats all ingredients without mashing the grapes.
Cover and refrigerate the salad for at least 30 minutes before serving to allow flavors to meld.