Combine the gochujang, sesame oil, gochugaru, mirin, soy sauce, sugar and garlic in a large bowl. Mix in the pork belly until coated on all sides. Let sit at room temperature for 30 minutes.
Heat a large non-stick skillet over medium-high heat.
Drain the excess marinade from the pork. Cook the pork in batches, making sure not to overcrowd the pan, flipping once, until cooked through and nicely charred, 5 to 6 minutes. Discard excess oil and wipe the skillet dry to cook next batch.
Serve the pork with rice, lettuce, perilla leaves, ssamjang, scallions and toasted sesame seeds.
