In a bowl, combine the Greek yogurt, minced garlic, lemon juice, lemon zest, salt, cumin, onion powder, smoked paprika, turmeric, pepper, cinnamon, red pepper flakes, and fresh parsley. Whisk until smooth and well combined—this creates a flavorful marinade base. Cut the chicken thighs into 1-inch pieces and add them to the bowl, stirring well to coat every piece evenly. Cover and refrigerate for at least 30 minutes (or up to 4 hours for deeper flavor). I find that letting the chicken marinate for the full time really helps the spices penetrate the meat and creates a much more authentic flavor.

Remove the marinated chicken from the refrigerator and let it sit at room temperature for 5 minutes. If air frying, preheat to 400°F and arrange the chicken pieces in a single layer in the basket, then cook for 20-24 minutes, shaking the basket halfway through to ensure even cooking. If pan-searing, heat 2 tablespoons oil in a large skillet over medium-high heat and cook the chicken in batches for 15-20 minutes total, stirring occasionally to cook all sides evenly. The chicken is done when golden-brown and cooked through. I prefer air frying because it crisps up the edges while keeping the inside juicy, but either method works beautifully.

While the chicken is cooking, shred the lettuce into 1/4-inch strips, thinly slice the red onion, and slice the tomato. Arrange these on a serving platter or in individual bowls for easy assembly. Lightly warm the pitas (either in the oven, toaster, or on the stovetop for just 30 seconds per side) so they're pliable and ready to hold the filling.

Transfer the cooked chicken from Step 2 to a serving platter. To assemble, fill each warmed pita with a portion of the cooked chicken, then top with lettuce, red onion, and tomato. Drizzle generously with tzatziki sauce. Serve immediately while the chicken is still warm and the pita is soft.