Marinate the beef short ribs in soy sauce, cooking sake, sugar, cornflour, black pepper and oil for 20 minutes.
Heat a large frying pan with 1 tablespoon oil over high heat. Stir-fry the garlic until aromatic, about 2-3 minutes. Add the onion, spring onions and salt and stir-fry until soft, 3-4 minutes.
Add the beef ribs and cook until 70% done, about 4-5 minutes. Mix in the Korean barbecue sauce and cornflour slurry and heat through for 2-3 minutes. Serve garnished with roasted sesame seeds.
Beef short ribs are available at your local butchers. You may need to pre-order them. You can also ask them to chop them into 2.5cm pieces.
Japanese soy sauce, cooking sake and Korean barbecue sauce can be purchased in Oriental speciality stores.