Japanese
Slice the onion into 5 mm half-moons and cut the beef into bite-size pieces.
Combine the dashi, sake, mirin, soy sauce and sugar in a wide pan and bring to a boil.
Add the onion and simmer for 5 minutes until it starts to soften.
Add the beef, separate the slices and skim off any foam as it rises.
Simmer over medium-low heat for 8-10 minutes until the beef is tender and the onion is soft and brown from the sauce.
Divide the hot rice among 4 large bowls and spoon the beef, onion and sauce over it.
Top with pickled red ginger and green onions and serve.