Cut the pork hind leg into bite-sized pieces.
Finely chop the onion, green onion, and garlic.
Make the marinade by mixing gochujang (Korean chili paste), red pepper flakes, soy sauce, sugar, minced garlic, black pepper, and sesame oil.
Add the marinade to the pork and mix well, then let it marinate for 20 minutes.
Heat cooking oil in a pan and stir-fry the onion and green onion over medium heat.
Add the marinated pork and stir-fry over high heat.
When the meat is cooked, add more green onion and stir-fry once more.
Finish by sprinkling sesame seeds on top.