Butterfly the steak to open up to a 1/4-inch thickness (or less). Place between two pieces of plastic wrap or parchment paper and pound until very thin. (See blog post and/or video for more detail).
1¼ lb strip steak
Meanwhile, bring a couple of cups of water to a boil in a medium-sized pot over high heat. Place the prepped scallions in a heatproof dish and pour the hot water over them, submerging them. Allow them to rest in the hot water for 40 seconds and then immediately remove them with tongs to a plate lined with paper towels.
4 bunches scallions
Place the beef on a sheet of plastic wrap and then sprinkle the top of the meat with salt and pepper (about 1/2 tsp of each). Place the scallions on the beef at one end. Using the plastic wrap to help you roll the beef tightly around the scallions. Continue rolling until you have a tightly formed roll. Use about 6 strands of kitchen twine/string to secure the roll.
Salt and black pepper
In a small bowl, mix together the water, soy sauce, sake, honey, and sesame oil.
¼ cup water, ½ cup soy sauce, ¼ cup sake, 2 tbsp honey, 1 tbsp sesame oil
Add the cornstarch to a platter and roll the negimaki in it until it is coated.
½ cup cornstarch
Heat the vegetable oil in a large skillet over medium-high heat.
2 tbsp vegetable oil
Place the beef roll in the skillet and use tongs to rotate it occasionally, until browned and seared all over, about 4 minutes.
Carefully pour the prepared sauce into the pan and over the roll. Turn the heat down to medium, and cook, spooning the sauce over the roll until cooked through, about another 4 to 5 minutes. The ends of the roll should be slightly pink (not bright red) once ready and the sauce should have thickened slightly.
Remove the roll from the skillet and place it on a cutting board and let rest for 5 minutes.
Meanwhile, strain the sauce into a small bowl. Use a sharp knife to slice the negimaki into about 1/2-inch pieces. Arrange on a platter and spoon some of the sauce over the slices. Sprinkle the sesame seeds over the top. Serve at once with additional sauce on the side.
1 tbsp sesame seeds