Step 1

Preheat the broiler and set an oven rack in the top position.

Step 2

Heat the oil in a small saucepan over medium heat. Add the ginger and cook until softened and fragrant, a few minutes. Add the garlic and cook for 1 minute more. Do not brown. Add the dry Sherry, soy sauce, tomato paste, brown sugar and water; bring to a boil, then turn the heat down and simmer gently until just slightly thickened, 8-10 minutes. Add the sesame oil and butter and stir until the butter is melted. Set aside.

Step 3

Season the steak on both sides with salt and pepper and place on a broiler pan (or rack on top of a baking sheet). Broil the steak to desired doneness, about 5 minutes per side for medium-rare. Using tongs, transfer the steak to a cutting board; cover with foil and let rest for 10 minutes to let the juices settle (don't rush this step or the juices will gush out of the steak when you cut it). Cut the steak into thin slices across the grain and serve with the sauce.