Cut the pork neck into bite-sized pieces.
Rinse the soybean sprouts thoroughly and set aside.
Slice the onion and green onion into thin strips.
In a bowl, mix together soy sauce, minced garlic, red pepper powder, sesame oil, and black pepper to make the marinade.
Add the marinade to the pork neck and mix well.
Stir-fry the pork in a pan, and when it is about halfway cooked, add the soybean sprouts and sliced vegetables.
Stir-fry everything over high heat until all ingredients are cooked through.
Finish by drizzling with sesame oil and sprinkling sesame seeds to taste.