Cut the pork hind leg into bite-sized pieces.
Chop the onion, green onion, and garlic.
Make a sauce using gochujang (Korean chili paste), red pepper flakes, soy sauce, sugar, garlic, black pepper, and other seasonings.
Add the sauce to the pork and let it marinate for 20 minutes.
Heat cooking oil in a pan and stir-fry the onion and green onion.
Add the marinated pork and stir-fry, then add garlic.
Stir-fry on high heat until the pork is fully cooked.
Transfer the finished stir-fried pork to a plate.