Make the sauce by mixing together the yogurt, curry powder, sugar and oil in a small bowl. Taste and adjust seasonings to your liking.
Peel and cut the onion into 1 inch cubes. Thread skewers alternating lamb cubes, onion dried apricot halves. Place them into a large resealable bag and pour in the sauce. Make sure the kabobs are evenly well coated. Refrigerate and allow to marinate overnight or for at least 8 hours.
Preheat grill to medium heat and lightly oil grate.
Grill the kabobs over medium coals for 8 to 10 minutes on each side, or to your desired doneness.