Cut small slits in chicken thighs to help absorb marinade and place them in a bowl
add in the grated onion, olive oil, garlic, yogurt, tomato paste, oregano, kosher salt, black pepper, and Aleppo pepper.
Coat chicken thoroughly in marinade.
Arrange marinated chicken on a piece of plastic wrap, tightly roll into a cylinder, and seal the ends. You might need to use 2 plastic wraps, make sure the marinade is not leaking.
Freeze for 6 to 8 hours to firm up.
Once ready to cook, remove it from freezer, and let it sit on the counter for 10 to 15 minutes. Slice the chicken thinly using a sharp knife.
Heat a pan over medium high heat. Pan-sear the sliced chicken doner in a with a drizzle of olive oil (if needed). Cook for about 1 minute per side. Avoid overcooking to keep the chicken juicy. And void overcrowding the pan otherwise the chicken will start steaming and won't get crispy.
Serve with pita or lavash, sumac onion and parsley, fries, pickles and tomatoes.