How to Make It
In a small skillet of boiling water, blanch the asparagus until bright green, about 1 minute. Using a slotted spoon, transfer the asparagus to a plate and pat dry. Add the scallions to the skillet and blanch until bright green, about 45 seconds; transfer to the plate and pat dry. Lightly season the vegetables with salt and lightly coat with sesame oil.
Set a slice of beef on a work surface and season with salt and pepper. Arrange an asparagus stalk and a scallion lengthwise on the meat; trim them flush with the meat. Roll up the meat around the asparagus and scallion and secure with a toothpick. Repeat with the remaining slices of beef, asparagus and scallions.
In a small bowl, mix the miso with the soy sauce, mirin, sugar and ginger. Put the beef rolls in a shallow baking dish and coat generously with the miso mixture. Let stand for 20 minutes.
Heat a grill pan over high heat. Lightly brush the pan with vegetable oil. Add the beef-and-scallion rolls and cook over high heat until nicely charred all over, about 1 minute per side. Transfer to a cutting board and remove the toothpicks. Slice each roll on the diagonal 1 1/2 inches thick. Arrange the slices on a platter, cut sides up, and serve right away.