For the ribs: 1) Sprinkle the brown sugar over the beef and mix well to evenly coat. Let sit at room temperature for 10 minutes while preparing the marinade.
2) Transfer the beef into a large sealable freezer bag (you may need two). Add the marinade, press out excess air from the bag and seal. Turn the bag over several times to ensure the beef is evenly coated. Refrigerate for at least 4 hours but preferably overnight.
3) Heat gas or charcoal barbecue to medium-hot. Drain excess marinade off the beef. Barbecue the short ribs, turning once, until cooked as desired, about 3 to 4 minutes each side.
4) Garnish with thinly-sliced spring onions if desired.
5) Serve whole rib pieces as a main course or cut into smaller pieces, using kitchen scissors, for a starter or party nibble.
For the marinade: 1) In a bowl, whisk together the remaining ingredients.
Cook's note: Korean-style short ribs can be found at most Asian markets. The cut, also known as flanken, refers to a strip of beef cut across the bone from the chuck end of the short ribs. Unlike American and European-style short ribs, which include a thick slice of bone-in beef, Korean-style short ribs are cut lengthwise across the rib bones. The result is a thin strip of meat, about 20 to 25cm in length, lined on one side with 2 1/2-cm thick rib bones. The thin slices make for fast cooking on the griddle.