Thinly sliced beef and sweet golden onions come together in a savory Japanese-style sauce made with mirin, soy sauce, garlic, and sesame oil. Inspired by my mother's stovetop preparation, this easy beef yakiniku is a flavorful family dinner served over steamed rice.
Heat a large, heavy-bottomed skillet over medium heat.
Add 1 tablespoon of vegetable oil, the sliced onions, and salt. Cook for approximately 15 minutes, stirring frequently, until the onions are softened and golden brown.
Transfer the onions to a bowl and set aside.
In a separate bowl, combine the mirin, soy sauce, minced garlic, sugar, sesame oil, and water. Stir until the sugar is mostly dissolved. Set aside.
Increase the skillet heat to medium-high and add the remaining tablespoon of vegetable oil.
Once the skillet is hot, add the thinly sliced beef in a single layer, working in batches if necessary. Cook for approximately 1–1½ minutes, then turn and cook for another 1–1½ minutes, or until browned.
Return all the cooked beef to the skillet and pour in the prepared sauce. Stir gently to coat the meat.
Add the onions and cook for another 2 to 4 minutes, stirring occasionally, until the sauce is heated through and the flavors are combined.
Taste and adjust the seasonings or sweetness as desired.
Serve over freshly cooked rice and garnish with sliced green onions or toasted sesame seeds, if desired.