Mix the beef, onion, parsley, garlic, cumin, coriander, salt and cinnamon just until combined. Shape into eight flattened logs, each about 4 inches long and 1/2 inch thick.
Heat the oil in a large skillet over medium-high heat. Add the kofta in one uncrowded layer and cook for 4 to 5 minutes per side, until browned and 160°F in the thickest part.
Meanwhile, stir the yogurt and lemon juice together. Slice the cucumber and wrap the pitas in a clean damp towel.
Microwave the wrapped pitas for 30 seconds or warm them briefly in a dry skillet until flexible.
Fill each pita with two kofta, cucumber slices and a quarter of the yogurt sauce. Serve while the meat is hot.