Place ribs on a broiler pan. Sprinkle with salt and pepper. Broil 4 to 5 inches from the heat for 10 minutes or until browned.
Place leeks in a 5- to 6-quart slow cooker. Place ribs on leeks. Add garlic, ginger, star anise, and dried chile pepper. In a medium bowl combine sherry, orange peel, orange juice, soy sauce, and brown sugar. Pour over ribs in cooker. Cover; cook on low-heat setting for 11 to 12 hours or on high-heat setting for 5-1/2 to 6 hours.
Using a slotted spoon or sieve, transfer ribs to platter; cover to keep warm. Strain cooking liquid; discard solids. Skim fat from cooking liquid. Sprinkle ribs with cilantro. Serve cooking liquid with ribs for dipping. Serve ribs with clementines.