Cut the pork into bite-sized pieces.
Slice vegetables such as onion and green onion.
In a bowl, mix pork with soy sauce, sugar, minced garlic, gochujang, and sesame oil to marinate.
Heat oil in a pan and stir-fry the green onion to bring out its aroma.
Add the marinated pork and vegetables to the pan and stir-fry.
Cook over high heat until the pork is done, then sprinkle sesame seeds if desired.