In a bowl or bag, place all of the chicken ingredients together and mix well. Marinate for up to 2 hours.
Once ready, place the chicken on a grill or in a pan and cook for about 3-4 minutes per side.
Mix all of the tzatziki sauce ingredients together and let sit for at least 1 hour before using.
Take a piece of pita bread and layer with the lettuce, chicken, tomato, red onion and tzatziki sauce.
