Finely chop the beef.
Finely chop the onion and green onion.
Heat cooking oil in a pan and sauté the onion and green onion.
Add the beef and stir-fry until cooked.
Season with soy sauce, sugar, and pepper.
Place the stir-fried beef over rice.
Drizzle mayonnaise on top.
Optionally, sprinkle with seaweed flakes and sesame seeds.