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 pieces and toss thoroughly to coat evenly. Cover and marinate for at least 15 minutes at room temperature, or refrigerate for up to 2 hours for deeper flavor.
02 - Heat a grill pan or 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 Greek yogurt, tahini if using, lemon juice, finely grated garlic, and salt and pepper to taste in a small bowl until smooth and well combined.
04 - Warm the pita breads and arrange on plates. Fill each pita with shredded lettuce, sliced chicken, halved cherry tomatoes, diced cucumber, sliced red onion, and chopped parsley. Drizzle generously with the yogurt sauce.
05 - Serve immediately while warm, accompanied by your choice of beverage.