In a large bowl, combine olive oil, cumin, coriander, smoked paprika, turmeric, cinnamon, garlic powder, onion powder, salt, black pepper, and lemon juice. Mix well to create a marinade. Add the chicken thighs, ensuring they are well coated. Cover and refrigerate for at least 1 hour, or overnight for best flavor.
Preheat your grill or a large skillet over medium-high heat. If using a skillet, add a little olive oil to prevent sticking.
Remove the chicken from the marinade and cook for about 6-7 minutes on each side, or until the internal temperature reaches 165°F and the chicken is nicely browned. Remove from heat and let it rest for 5 minutes.
While the chicken is resting, prepare the creamy garlic sauce. In a small bowl, combine the Greek yogurt, mayonnaise, minced garlic, apple cider vinegar, and a pinch of salt. Mix until smooth and creamy.
Slice the chicken into thin strips. Serve in pita bread or flatbreads, topped with sliced cucumbers, tomatoes, red onion, and a generous drizzle of the creamy garlic sauce. Garnish with fresh parsley if desired.