Boil rice. For original Japanese rice enjoyment, it is best to use American or Korean short-grain rice, but commercial long-grain rice also works for this dish.
Slice meat (it works best when it is slightly frozen or you order it from the butcher). Slice the onions (don`t have to be too thin).
Briefly bring the ingredients for the sauce to the boil in a saucepan. Then add meat and onions and simmer on medium heat for 5-6 minutes. Divide the rice in 4 deep bowls and pour the meat and sauce over them.
In Japan you eat a (miso) soup with it.
Tip: You can also use ground beef instead of the thinly sliced beef.