Preheat your oven to 300°F (150°C).

In a large Dutch oven or heavy pot, heat the vegetable oil over medium-high heat. Add the short ribs and sear them on all sides until browned, about 3-4 minutes per side. Remove the ribs and set aside.

In the same pot, add the chopped onion and sauté until translucent, about 5 minutes. Stir in the minced garlic and grated ginger, cooking for an additional minute until fragrant.

In a bowl, whisk together the soy sauce, brown sugar, rice vinegar, sesame oil, gochujang, and beef broth. Pour this mixture into the pot with the onions and garlic, stirring to combine.

Return the seared short ribs to the pot, making sure they are submerged in the sauce. Bring the mixture to a simmer.

Cover the pot with a lid and transfer it to the preheated oven. Braise for 2.5 to 3 hours, or until the meat is tender and falling off the bone.

Once done, remove the pot from the oven and let it rest for 10 minutes. Skim off any excess fat from the surface of the sauce.

Serve the short ribs over rice or noodles, drizzled with the braising sauce, and garnish with sliced green onions and sesame seeds.