01 - In a mixing bowl, whisk together the gochujang, soy sauce, brown sugar, sesame oil, minced garlic, grated ginger, rice vinegar, mirin if using, and black pepper until a smooth, uniform paste forms.
02 - Place the trimmed lamb ribs in a large resealable bag or shallow dish. Pour the marinade over the ribs, massaging the bag or turning the ribs to ensure every surface is thoroughly coated. Seal and refrigerate for a minimum of 4 hours, preferably overnight for deepest flavor penetration.
03 - Preheat the oven to 320°F. Remove the ribs from the refrigerator and transfer them from the marinade to a wire rack set over a rimmed baking sheet, reserving all excess marinade. Tightly cover the ribs with aluminum foil.
04 - Roast the covered ribs in the oven for 1 hour. While the ribs cook, pour the reserved marinade into a small saucepan, stir in the honey, and simmer over low heat for approximately 5 minutes until the mixture thickens into a glossy glaze.
05 - Increase the oven temperature to 400°F. Remove the foil from the ribs and brush them generously on all sides with the honey-glaze mixture. Return the uncovered ribs to the oven and roast for 10 to 15 minutes until the exterior is deeply caramelized and lightly charred in spots.
06 - Remove the ribs from the oven and let them rest for 5 minutes to allow the juices to redistribute. Squeeze fresh yuzu juice generously over the surface of the ribs.
07 - Scatter the sliced scallions, toasted sesame seeds, and sliced red chili over the ribs. Cut between the bones into individual ribs and serve immediately with steamed rice or pickled vegetables.