Wash the rice about three times and soak it in cold water for at least 30 minutes.
2
Mix 2 cups water with 0.5 tablespoon chicken bouillon powder and 0.5 tablespoon soy sauce, and set aside.
3
Place thinly sliced beef in a bowl and add soy sauce, oyster sauce, mirin, sugar, sesame oil, neutral oil, and black pepper; massage until well combined.
4
Smash and finely chop garlic, thinly slice the white parts of green onions and separately chop the green parts, and dice half an onion.
5
Thinly slice shiitake mushrooms and cut button mushrooms into quarters.
6
Heat 2 tablespoons oil in a pot over medium-high heat. Once hot, place marinated beef in a single layer and sear for 1–2 minutes until golden brown; flip and stir-fry for about 2 minutes, then remove and set aside.
7
Add 1 tablespoon oil to the same pot and heat. Once hot, add garlic, white parts of green onions, and onion; sauté for about 1 minute until fragrant.
8
Add mushrooms and stir-fry for about 3 minutes until coated with the aromatic oil.
9
Add the drained rice and stir for about 1 minute to coat the grains evenly with flavors.
10
Pour in the seasoned water and keep stirring until it comes to a boil, scraping the bottom of the pot to deglaze.
11
Reduce heat to low, place the cooked beef on top of the rice, cover with a lid, and simmer for about 15 minutes.
12
Remove from heat and let it steam for another 10 minutes without lifting the lid.
13
Open the lid, sprinkle with green onion tops and a pat of butter, and serve.