This is a rice bowl with beef (gyuuniku), egg (tamago), onion (tamanegi) over rice (meshi), so the Japanese name is gyu-tama-meshi. Mix the soft poached egg with the beef and onion and rice before eating.
Make the poached egg. For every liter of water, add 2 tablespoons of vinegar and a pinch of salt. Bring the water to a boil in a pan, then lower the heat.
Mix the water around vigorously with chopsticks to create a vortex. Drop an egg into the vortex.
When the egg is poached to your preferred hardness, remove from the pot. The vinegar in the water helps firm the egg whites.
Cut the beef into bite-sized pieces. Remove the roots off the enoki mushrooms and cut in half. Slice the onion into wedges.
Heat oil in a pan and stir fry the beef over medium heat. When the beef turns pale, add the onion, and stir-fry until wilted.
Add the enoki mushrooms and all the ingredients under A (soy sauce, sugar, water). Mix quickly, cover with a lid and simmer for 3 minutes.
Remove the lid and continue cooking until the sauce has reduced down to almost nothing - and it's done.
Serve the rice into two large rice bowls. Ladle the sukiyaki from Step 7 on top, and sprinkle with chopped Japanese leek. Top with the poached egg. Sprinkle shichimi spice and enjoy.
Story Behind this Recipe
When I was a child, I used to eat leftover sukiyaki mixed with rice, like fried rice. It was so delicious that I wanted to recreate that flavor easily.
When you make the poached egg, by creating a vortex in the water by stirring it with chopsticks, the white will wrap itself around the yolk. If the white spreads out, flip it over the yolk with a fork. Use low heat, and don't let the water boil.