Begin by trimming any excess fat from the bone-in beef short ribs, patting them dry with a paper towel. Season generously with salt and freshly cracked pepper.

In a large skillet, heat a tablespoon of oil over medium-high heat. Once shimmering, carefully add the ribs, searing for about 3-4 minutes on each side until golden crusted.

In a mixing bowl, whisk together the soy sauce, hoisin sauce, mirin, brown sugar, minced garlic, grated ginger, and optional chili flakes.

Preheat your oven to 275–300°F (135–150°C). In a Dutch oven, place the seared ribs and pour the marinade over. Add sliced onions, cover, and roast for 3–4 hours, basting every hour.

Once fork-tender, remove the ribs and transfer the braising liquid to a skillet over medium heat. Simmer and reduce for about 10-15 minutes until thickened.

For added caramelization, switch to broil mode and broil the roasted ribs for 2-3 minutes.

Plate the tender ribs over steamed rice, noodles, or roasted vegetables, drizzling reduced glaze over and garnishing with chopped green onions and sesame seeds.