Cut the pork neck into bite-sized pieces.
Rinse the bean sprouts thoroughly and drain the water.
Thinly slice onion, green onion, hot pepper, and garlic.
In a bowl, mix gochujang, chili powder, minced garlic, soy sauce, and sugar to make the seasoning sauce.
Heat oil in a pan and stir-fry the pork neck over high heat.
When the pork is halfway cooked, add onion, green onion, hot pepper, and garlic, and stir-fry together.
Add the seasoning sauce and mix well while stir-frying.
Add the bean sprouts, cover, and cook for 2-3 minutes.
Uncover and stir-fry quickly over high heat to evaporate the moisture and finish.