Pound the chicken to tenderize. Mix olive oil and all the marinade ingredients in a plastic bag or shallow pan. Add the chicken to the bag or pan and coat with the marinade. Seal the bag or cover the pan with plastic wrap and let marinate in the refrigerator for 2 hours or overnight.
Remove the chicken from the marinade and heat a cast iron skillet or a frying pan on medium-high heat. Add the chicken to the pan. There should be enough oil in the marinade so that you don’t have to add oil. Cook the chicken for 5 minutes a side or until cooked through.
Mix all Tzatziki Sauce ingredients together.
Wrap chicken in warm pita bread with Tzatziki Sauce, tomatoes, sliced onions, sliced cucumbers.