Cut the thinly sliced pork neck into bite-sized pieces.
Slice the onion and green onion thinly.
In a bowl, mix soy sauce, sugar, minced garlic, sesame oil, and pepper to make the sauce.
Combine the pork neck with the sauce and mix well.
Add cooking oil to a pan and stir-fry the pork neck and vegetables.
Stir-fry over high heat until the pork is fully cooked.
Transfer to a plate and sprinkle with sesame seeds.