Preheat the oven to 350°F (175°C).
Score the skin of the pork belly in a crosshatch pattern.
Heat vegetable oil in a heavy oven-safe pan over medium-high heat. Sear the pork belly, skin-side down, for 3-4 minutes, until the skin is golden and crispy. Flip the pork belly over and sear the other side for another 2-3 minutes.
Remove the pork belly from the pan and set aside.
In the same pan, add sesame oil, garlic, and ginger. Sauté for about 1 minute until fragrant.
Add soy sauce, brown sugar, honey, rice vinegar, and gochujang to the pan. Stir until the sugar is dissolved.
Return the pork belly to the pan, skin-side up. Spoon some of the sauce over the top.
Transfer the pan to the oven and roast for 45 minutes to 1 hour, basting the pork belly every 15 minutes with the sauce.
Once the pork belly is tender and caramelized, remove from the oven and let it rest for 10 minutes.
Slice the pork belly into thick pieces and drizzle with the sauce from the pan. Garnish with sesame seeds and green onions before serving.
