01 - In a mixing bowl, whisk together 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 to ensure every surface is evenly coated. Seal tightly and refrigerate for at least 4 hours, preferably overnight for maximum flavor penetration.
03 - Preheat the oven to 320°F. Remove the ribs from the refrigerator and take them out of the marinade, reserving any excess marinade in a bowl. Arrange the ribs on a wire rack set over a rimmed baking sheet and cover tightly with aluminum foil.
04 - Roast the covered ribs 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 5 minutes until slightly thickened into a glossy glaze.
05 - Increase the oven temperature to 400°F. Uncover the ribs and brush generously on all sides with the honey-glaze mixture. Return to the oven and roast uncovered for 10 to 15 minutes until the surface is deeply caramelized and lightly charred in spots.
06 - Remove the ribs from the oven and allow them to rest for 5 minutes. Squeeze yuzu juice generously over the ribs, allowing the bright citrus to mingle with the caramelized glaze.
07 - Transfer the ribs to a serving platter. Scatter sliced scallions, toasted sesame seeds, and sliced red chili over the top. Serve immediately with steamed rice or pickled vegetables.