Marinate the chicken: Put the marinade ingredients in a large ziplock bag. Add the chicken, seal the bag, and massage from the outside so every piece is coated. Marinate overnight for the best flavor, or for at least three hours if you're short on time.
Yogurt sauce: In a bowl, combine the ingredients for the yogurt sauce and stir. Cover and refrigerate until needed; it will keep for up to three days.
Preheat: Heat 1 tablespoon of oil in a large non-stick pan over medium-high heat, or lightly grease the hotplate or grills of a barbecue and heat to medium-high.
Cook the chicken: Put the chicken on the grill or in the skillet and cook for 4 to 5 minutes on the first side, or until well browned. Turn and cook for 3 to 4 minutes on the second side, which cooks more quickly.
Rest: Take the chicken off the heat, loosely wrap it in foil and let it rest for five minutes.
Serve: Arrange the chicken on a platter with flatbreads, salad, and the yogurt sauce.
Make a wrap: Spread a piece of flatbread with yogurt sauce, top with lettuce, tomato, and chicken shawarma, then roll it up and enjoy!