Slice the chicken thinly and lightly smash it flatter so it cooks fast and gets that kebab texture.
In a large bowl mix olive oil, lemon juice, garlic, onion powder, paprika, sumac, salt and pepper.
Add chicken and coat really well. Cover and marinate in the fridge for at least 30 minutes (longer if you can).
Thread the chicken onto a vertical shawarma spit/rod. Place half an onion on top so the juices drip down while cooking.
Roast in the oven at 200° until cooked through and golden on the edges. Slice off the cooked chicken layers to serve.
For the tahini yoghurt sauce, whisk together tahini, Greek yoghurt, lemon juice, salt, sumac, water and cumin until smooth and drizzly.
For the pickled onions, add sliced onions, lemon juice, olive oil, salt and sumac to a bowl and mix together until the onions soften and turn slightly pink. Let sit for 15-30 minutes.
Warm wraps and fill with lettuce, tomato, chicken, pickled onions and tahini yoghurt sauce. Wrap, roll and serve.
