Preheat a large pan over medium heat. If the beef is well-marbled, no additional oil is needed.

Add the first batch of beef slices in a single layer without overcrowding. Leave untouched until juices appear on the surface (about 15-20 seconds), then flip. Remove once the bottom is golden brown. Repeat with remaining beef.

Wipe the pan clean with a paper towel if needed. Increase heat to medium-high and return all the seared beef and its juices to the pan.

Pour the yakiniku sauce over the beef and flip the pieces to coat thoroughly. Cook until the sauce bubbles and coats the meat; avoid overcooking.

Divide the cooked rice into donburi bowls. Layer the yakiniku beef over the rice.

Top with sliced green onions and a sprinkle of sesame seeds. Serve immediately.