1. Prepare the marinade by mixing the chicken with 62g (¼ cup) of the yogurt, cardamom, cinnamon, nutmeg and ½ teaspoon of each of the oregano and salt. Set aside to marinate for at least 30 minutes.
2. Prepare the yoghurt and tahini sauce by mixing the tahini paste with the remaining yoghurt, oregano and salt. Add the white pepper and lemon juice. Stir and set aside.
3. In a large non-stick frying pan, heat the oil over a medium - high heat and add the chicken mixture.
4. Stir the chicken, cover and cook for 7-10 minutes on a low-medium heat, or until the chicken is cooked through. Remove from the heat and set aside.
5. To assemble, place some chicken on to a warmed pita bread. Top with onion, cucumber, lettuce & parsley.
6. Spoon some of the tahini sauce over the top and sprinkle lightly with the sumac powder. Gently fold the pita bread.
You can also use aluminum foil to fold the wrap; this will avoid spillage and hold the wrap together well.