Cut the pork into bite-sized pieces.
Slice the onion, green onion, and chili pepper into thin strips.
In a bowl, make the seasoning sauce by mixing red chili powder, soy sauce, minced garlic, sugar, black pepper, and sesame oil.
Add the seasoning sauce to the pork and mix well to coat evenly.
Heat cooking oil in a pan and stir-fry the onion, green onion, and chili pepper.
Add the seasoned pork and stir-fry over high heat.
Once the meat is cooked through, transfer to a plate and serve.