In a large baggie or bowl, mix together two cups yogurt with the olive oil, cumin, coriander, paprika, lemon juice, cinnamon and garlic. Add the strips of lamb meat and marinade at least eight hours or overnight.
Heat a cast iron grill pan over high heat and grease with cooking spray.. Add the strips of marinated lamb, letting most of the excess yogurt drip off. Cook for 5-8 minutes, until cooked through - at least 145 F for a pink center, 160 F for medium well.
Just prior to serving, stir together the remaining yogurt, cucumber and dill. Serve room temperature or chilled. Warm the pita bread in the microwave for thirty seconds. Fill the warm pitas with the cooked lamb and lettuce, onions, tomatoes and yogurt sauce as desired. Enjoy!