Mix the water and cucumber slices. Place in the refrigerator until ready to serve.
Prep the ingredients per instructions above
In a bowl mix the chicken, garlic powder, cumin, salt and pepper, and half of the cilantro until fully combined.
Make the sauce: Mix all of the ingredients for the sauce in a bowl until smooth. Add water, about 1 tsp at a time as needed to thin it out to a creamy sauce. Season with salt and pepper to taste. Set aside.
Heat a nonstick pan on medium heat. Once hot, add the oil. Brown the chicken mixture until it is no longer pink and cooked through. Season with salt and pepper to taste as needed.
Warm the taco shells on both sides in a pan over medium heat for approximately 20 seconds per side.
Layer the taco shells with chicken mixture, lettuce, tomato, onion, sauce, and feta. Serve with hummus, pita, and cucumber water. Serve cucumber water over ice if desired.