Cut slits ⅓ of the way into the 270 grams steak ¼-inch apart. Flip the steak over and repeat, holding the knife at the same angle.
270 grams steak
Mix the 350 grams onions and ¼ teaspoon salt and surround the steak in onions. Cover and marinate in the fridge overnight.
350 grams onions, ¼ teaspoon salt
When the steak is done marinating, brush off all of the onions from the meat and set the onions aside. Season both sides of the steak with Black pepper.
Black pepper
Preheat a frying pan over medium-high heat until very hot. Add the 1 tablespoon vegetable oil and then add the steak.
1 tablespoon vegetable oil
Fry on one side until nicely browned, and then flip and fry the other side.
When the steak is cooked to your liking, transfer it to a plate and let it rest while you prepare the onions.
Turn down the heat and add the onions. Stir-fry these until they've started to brown around the edges, but they still hold their shape (about 6 minutes).
Add the 2 tablespoons soy sauce and continue stir-frying until the liquid has evaporated and the soy sauce starts to smell toasty.
2 tablespoons soy sauce
Add the ⅓ cup red wine and boil until it no longer smells like alcohol.
⅓ cup red wine
To finish the sauce, add the 2 tablespoons cultured unsalted butter and vigorously whisk it in to thicken the sauce.
2 tablespoons cultured unsalted butter
For the rice, fold the minced 70 grams umeboshi into the 2 servings Japanese short grain rice until evenly distributed.
2 servings Japanese short grain rice, 70 grams umeboshi
Fill two bowls with the ume rice, and then top with the sliced steak. Finish each bowl with a mound of onions, and garnish with some chopped Scallions.
Scallions