How to Make It
Light a grill. On a baking sheet, rub the steak and whole scallions with the 2 tablespoons of oil; season with salt and pepper.
Oil the grill grate. Grill the steak for 20 to 25 minutes, turning occasionally, until an instant-read thermometer inserted in the center registers 125° for medium-rare. Transfer the steak to a cutting board and let rest for 15 minutes.
Meanwhile, grill the 16 whole scallions over moderate heat, turning, until lightly charred and tender, about 3 minutes. Transfer 8 of the scallions to a platter. Chop the rest and transfer to a bowl; let cool. Add the sliced raw scallions, cilantro, chiles, lime juice and 2 tablespoons of ginger; mix well.
Thinly slice the steak across the grain and arrange on the platter. Spoon the scallion relish on the steak and garnish with freshly grated ginger.