Place the steak in the freezer for 10-15 minutes. When chilled, very thinly slice the steak against the grain into strips.

Make the sauce: combine the soy sauce, cornstarch, sake, oyster sauce, and mirin in a small dish until smooth, then set aside.

Heat the butter in a large skillet over medium-high heat. When the butter foams and browns, add the steak in one layer and cook for about 3 minutes on each side until browned and crispy at the edges. Don't crowd the pan; you might need to cook the steak in two batches. Remove the steak to a dish.

To the same skillet, add the bok choy, chili pepper, and garlic. Stir for 2 minutes to start to cook, then pour in the sauce. Reduce the heat to medium-high and add the steak , white parts of the scallions, and baby corn to the skillet. Stir everything together, and taste: add more soy sauce if you'd like. If the sauce thickens very quickly, splash in water a bit at a time to thin it.

Serve over rice, if desired, topped with the scallion greens.

Enjoy!