Thinly slice your onion and set aside
If you’re slicing your own beef, use semi-frozen meat for cleaner cuts
Over medium heat, combine soy sauce, mirin, sake, dashi powder, and onion
Let it come to a simmer and cover the pan with a lid or aluminum foil
Cook until onion is soft and translucent (about 3-5 minutes)
Gently separate the thinly sliced beef and add it to the pan
Cook for 1–2 minutes, flipping the beef gently, until the beef is no longer pink. Don’t overcook. Thin slices of beef cook very fast.
Prepare bowl of hot steamed Japanese rice.
Spoon the beef and onion mixture over the rice.
Drizzle some sauce from the pan over the top
Top with green onions, a soft-boiled egg, pickled ginger, or a dash of shichimi togarashi for extra flavor and color