1. Cook the rice in the water for 10 minutes after resuming the boiling under cover.
2. Mince the beef into thin slices. Diving in boiling water for a few minutes then reserve.
3. Heat a skillet over medium heat and mix in sugar, soy sauce, mirin and sake. When the mixture is bubbling, add the beef, cover well with sauce.
4. Before complete evaporation, reserve the beef and add 1/4 of cube and 100ml of water to the sauce.
5. Add the chopped onion and cover. When boiling, add the beef and simmer for 5 minutes.
6. Serve rice in bowls, covered with beef.