Thinly slice the onion and green onion.
Cut the beef brisket into bite-sized pieces.
Heat cooking oil in a pan and stir-fry the beef brisket over high heat.
Once the brisket is cooked, add the onion and green onion and stir-fry together.
Season with soy sauce, sugar, minced garlic, and pepper.
Place the stir-fried ingredients over rice and finish with a sprinkle of sesame seeds.