Slice the green onions thinly.
Cut the beef into bite-sized pieces.
In a bowl, mix together gochujang, soy sauce, sesame oil, minced garlic, and sugar.
Add the sliced green onions and beef to the marinade and mix well.
Heat cooking oil in a pan and stir-fry the marinated beef.
Stir-fry over high heat until the beef is fully cooked.