In a large bowl, combine the shredded chicken and mashed avocado. Mix until well combined.

Add the Greek yogurt, Dijon mustard, lemon juice, red onion, celery, garlic powder, salt, and pepper. Stir until all ingredients are evenly incorporated.

If using, fold in the chopped cilantro for added flavor.

Taste and adjust seasoning if necessary.

Serve immediately on a bed of greens, in a sandwich, or in lettuce wraps.