1. In a bowl, mix chicken, crumbs, egg yolk, onion, turmeric, and 1/4 teaspoon salt. Cover and chill at least 30 minutes or up to 1 day.
2. Divide chicken mixture into 4 equal portions. Dipping your hands frequently in water to keep mixture from sticking, pat each portion around a skewer (flat metal ones are easiest to handle) to form a log 1 inch thick and about 7 inches long.
3. One skewer at a time, lay chicken on a lightly oiled barbecue grill over a solid bed of hot coals or high heat on a gas grill (you can hold your hand at grill level only 2 to 3 seconds) and rotate quickly to firm up the surface of the meat. When all skewers are on the grill, close lid of gas grill. Rotate skewers every 2 to 3 minutes until meat is lightly browned and firm, not squishy, at skewer (cut to test), about 10 minutes total.
4. Cut or push meat off skewers. Add salt to taste.