Cut pork, onion, green onion, and garlic into bite-sized pieces.
In a bowl, mix gochujang, soy sauce, minced garlic, chili powder, sugar, and pepper to make the marinade.
Add the marinade to the pork and let it sit for 10 minutes.
Add a small amount of olive oil to a pan and stir-fry the onion and green onion.
Add the pork and stir-fry on high heat until cooked through.
Add a little sesame oil at the end and serve on a plate.