Make the marinade. In a bowl, mix the gochujang, soy sauce, rice wine, sugar, sesame seed oil, garlic, ginger, chopped shallot and black pepper.
Add the pork slices to the marinade. Cover the bowl and let sit in the fridge for a couple of hours.
Heat the cooking oil in a thick-bottomed frying pan. Swirl the pan to coat the entire bottom with oil.
Lay the pork slices on the pan in a single layer. Cook over high heat until the marinade starts to caramelize, about four minutes. Flip the pork belly slices over and cook for another three or four minutes.
Serve the Korean spicy marinated pork belly slices over rice. Garnish with sliced scallions and toasted sesame seeds.