Combine all the sauce ingredients (soy sauce, dark soy sauce, oyster sauce, mirin, sugar, and ground black pepper) in a small bowl and mix well.
3 Tbsp soy sauce, 1.5 Tbsp dark soy sauce, 1.5 Tbsp oyster sauce, 2 Tbsp mirin, 2 tsp granulated sugar, 1 tsp ground black pepper
Toss the thinly sliced beef with about 3 tablespoons of the sauce and set aside to marinate while you prep everything else.
12 oz thinly sliced beef
Wash the rice thoroughly and drain it completely in a strainer. You don't want any extra water because the liquid measurement is precise to ensure the rice is not soggy.
2 cups white rice
Add the drained rice to the rice cooker along with the minced garlic, beef broth, salt, and 3 tablespoons of the sauce. Stir until evenly combined, then layer the corn and sliced onion on top. Turn on the rice cooker using the normal or white rice setting.
2 cloves garlic, 2 cups low-sodium beef broth, ¼ tsp salt, ½ cup corn kernels, ½ yellow onion
With about 15 minutes left on the cooking cycle, lift the lid and add the marinated beef and butter on top of the rice in a single layer. Close the lid and let it finish cooking through.
2 Tbsp unsalted butter
Once the rice cooker switches off, sprinkle in the chopped green onions and give everything a quick stir to combine.
Chopped green onions
Plate with rice in the center and beef around the edges. Top with sesame seeds and another knob of butter, add freshly cracked black pepper, and drizzle with the remaining sauce.
Sesame seeds, Freshly cracked black pepper, Butter