In a mixing bowl, combine olive oil, minced garlic, cumin, paprika, turmeric, coriander, cinnamon, cayenne pepper, salt, pepper, and lemon juice. Whisk until well blended to create the marinade.
Add the chicken thighs to the bowl and coat them thoroughly with the marinade. Cover and let marinate in the refrigerator for at least 30 minutes (or up to 2 hours for more flavor).
Preheat your grill pan or skillet over medium-high heat. Remove the chicken from the marinade, allowing excess marinade to drip off.
Place the chicken in the preheated pan and cook for about 6-7 minutes on each side, or until fully cooked and the internal temperature reaches 165°F (75°C).
Once cooked, remove the chicken from the heat and let it rest for a few minutes before slicing it into thin strips.
Warm the pita bread in the same pan or in a microwave for about 10-15 seconds.
Assemble your Chicken Shawarma by placing sliced chicken on the pita, topping it with cucumbers, tomatoes, and lettuce. Drizzle with tahini sauce or garlic sauce as desired.
Serve immediately with your choice of sides.