Heat the oil in a large frying pan over medium high heat.
Add ½ cup dashi, sake, sugar, mirin, and soy sauce.
Cover the lid and bring the sauce to boil. Once the sauce is boiling, add the sliced onions and spread them out. Cover to cook until tender.
When the onion is tender, add the beef and cook until no longer pink. Skim the foam or fat with a fine mesh sieve.
Serve the meat and sauce over steamed rice.
Top with chopped green onion and pickled red ginger. If you like to add an egg, serve with Onsen Tamago. Alternatively, you can pour beaten egg over the meat when it’s almost finished cooking in the pan.
DONE!