Brush steak all over with 2 tbsp. vinaigrette; season. Grill over medium-high, turning once, until browned, 12 minutes for medium-rare. Transfer to cutting board; let rest 10 minutes. In bowl, toss remaining ingredients with 1 1/2 tbsp. vinaigrette; season. Thinly slice steak against the grain; toss with salad.
