Preheat your oven to 300°F (150°C).

In a mixing bowl, whisk together the 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 shallow dish and pour the prepared marinade over them, ensuring they are thoroughly coated. Cover and marinate for at least 30 minutes at room temperature or refrigerate overnight.

Heat a tablespoon of oil in the same pot over medium-high heat. Sear the marinated short ribs for 2-3 minutes on each side until golden-brown.

Pour the remaining marinade over the short ribs and cover with a tight-fitting lid. Roast in the preheated oven for approximately 3 hours until fork-tender.

Mix the cornstarch with water to form a slurry. Pour into the pot with the remaining juices and simmer over medium heat for about 5 minutes, stirring until thickened into a glaze.

Preheat the oven broiler and brush the thickened glaze over the short ribs. Broil for 5-10 minutes until the glaze is caramelized and bubbling.

Let the caramelized short ribs rest on a cutting board for about 15 minutes before slicing.