In a medium bowl combine the Greek yogurt, mayo, fresh dill, onion and garlic powders, seasoned salt, and black pepper.
Stir in the chopped chicken and celery. Let it chill in the refrigerator for at least 30 minutes. The longer the better so the flavors can fully combine.
Separate out the lettuce cups, and fill them with the chicken salad. Top with avocado slices and a drizzle of sriracha if desired.
If time allows, wash the head of lettuce and chill ahead of time, this will help get the lettuce as crisp as possible.
You can always used canned chicken, or baked chicken breasts, but I just love the convenience of a rotisserie chicken every week!
This salad is also great in a pita pocket, on toast, or scooped up with snack crackers. Enjoy!