For serving:
2 scallions, white and green parts thinly sliced
Toasted sesame seeds
Steamed white rice
Kimchi (optional)
In a small mixing bowl, combine the soy sauce, garlic, vinegar, sesame oil, sake (if using), chili sauce, ginger, and black pepper. Arrange the short ribs in a single layer in a nonreactive baking dish. Pour the marinade over the ribs, and turn to coat. Cover and refrigerate for 4 hours. In the meantime, skewer the garlic on toothpicks or a bamboo skewer.
When ready to cook, set up your grill or hibachi for direct grilling and heat to high. Brush and oil the grill grate. Drain the ribs and discard the marinade. Arrange the beef ribs in a single layer on the grate along with the skewered garlic. Grill until the ribs are sizzling and browned on both sides, 2 to 4 minutes per side, and the garlic is browned.
If desired, cut the ribs into bite-size portions with kitchen shears. Transfer to a platter or plates and sprinkle with the scallions and sesame seeds. Serve with white rice and kimchi, if desired.