In a bowl, whisk together soy sauce, brown sugar, rice vinegar, sesame oil, minced garlic, grated ginger, and black pepper until well combined.

Place the beef short ribs in a large resealable bag and pour the marinade over the ribs. Seal the bag and refrigerate for at least 4 hours, preferably overnight.

Preheat the oven to 300°F (150°C).

Remove the short ribs from the marinade and pat them dry with paper towels.

In a skillet over medium-high heat, sear the short ribs on all sides until browned, about 3-4 minutes per side.

Transfer the short ribs to a roasting pan and pour the marinade over them.

Cover the roasting pan with foil and roast in the preheated oven for 3 hours.

After 3 hours, remove the foil and increase the oven temperature to 400°F (200°C).

Roast for an additional 1 hour, basting the ribs with the pan juices every 20 minutes, until the ribs are tender and caramelized.

Remove from the oven and let rest for 10 minutes before serving.

Garnish with sliced scallions and serve with rice or vegetables.