Cut the beef into bite-sized pieces.
Finely chop the onion.
Heat cooking oil in a pan and stir-fry the beef and onion.
Add soy sauce, sugar, and cooking wine to season the beef.
Place the stir-fried beef on top of rice.
Drizzle mayonnaise evenly over the beef.
Finish with bonito flakes, chopped green onion, and seaweed flakes.