1. Trim thick outer layer of fat from ribs; discard. Rinse meat and pat dry.
2. On the meaty side of each rib, 1/4 inch in from the edge opposite the bone, make a cut the length of the rib, down into meat but not quite through it. Turn the rib over. About halfway between bone and first cut, make another lengthwise cut almost through meat. Flip the rib over again and make a third lengthwise cut parallel to and around the bone almost through meat, leaving bone attached. Pull out to unfold meat.
3. In a 1-gallon heavy plastic food bag, combine soy, sherry, sugar, and ginger; shake to mix. Add short ribs to bag, seal, and turn over to coat meat with marinade.
4. Set bag in a bowl; chill at least 30 minutes or up to 1 day, turning several times. Remove ribs and discard marinade.
5. Lay ribs, pulled open so meat is flat, on a 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). Close lid; open vents for charcoal. Brown meat, turning once, 7 to 10 minutes. Transfer to a platter.