In a bowl, mix the olive oil, cumin, coriander, paprika, turmeric, garlic powder, cayenne pepper, salt, and pepper to create a marinade.
Add the chicken thighs to the bowl, ensuring they are well coated. Cover and marinate in the refrigerator for at least 1 hour, or up to overnight for more flavor.
Preheat your grill or stovetop grill pan over medium-high heat.
Grill the marinated chicken thighs for about 6-7 minutes on each side, or until the internal temperature reaches 165°F (75°C). Remove from the grill and let rest for 5 minutes.
While the chicken is resting, prepare the tahini sauce by mixing the Greek yogurt, tahini, lemon juice, and a pinch of salt in a small bowl. Stir until smooth and creamy.
Slice the grilled chicken into thin strips.
Warm the pita breads on the grill for about 1 minute on each side, just until soft and pliable.
To assemble, spread a generous spoonful of the tahini sauce inside each pita. Add sliced chicken, diced cucumber, tomatoes, and red onion.
Garnish with fresh parsley and drizzle with extra tahini sauce if desired.
Fold the pita and serve immediately while warm.
Notes
Marinating the chicken overnight enhances the flavor.