01 - In a large bowl, combine olive oil, minced garlic, paprika, cumin, oregano, coriander, chili powder, lemon juice, salt, and black pepper. Add the chicken and toss thoroughly to coat evenly. Cover and marinate for at least 15 minutes at room temperature, or refrigerate up to 2 hours for deeper flavor.
02 - Heat a grill pan or large skillet over medium-high heat. Cook the marinated chicken for 6 to 7 minutes per side until fully cooked through with a golden char. Transfer to a cutting board and rest for 5 minutes before slicing thinly against the grain.
03 - While the chicken rests, whisk together the Greek yogurt, tahini if using, lemon juice, grated garlic, and season with salt and pepper in a small bowl until smooth and well combined.
04 - Warm the pita breads and lay them open on plates. Layer each with shredded lettuce, sliced chicken, halved cherry tomatoes, diced cucumber, red onion slices, and chopped parsley. Drizzle generously with the yogurt sauce.
05 - Serve the filled pitas immediately while warm. Pair with a crisp white wine or sparkling water with a wedge of lemon.