Cut the outside skirt beef into bite-sized pieces.
Prepare the vegetables such as onion and scallion.
Marinate the beef with soy sauce, minced garlic, sugar, and black pepper.
Heat cooking oil in a pan and stir-fry the beef.
When the beef is half-cooked, add the vegetables and stir-fry together.
Once all ingredients are cooked, finish with a drizzle of sesame oil.