Flank steak stars in a satisfying meal that guests can assemble to their liking. We are big fans of tomatillo salsas for their bright, slightly acidic flavor, which is complemented here by creamy avocado.
04Meanwhile, cut romaine crosswise into thin shreds. Quarter avocados lengthwise, then pit, peel, and cut lengthwise into 1/4-inch-thick slices.
05While steak is standing, stack tortillas, wrapped completely in dampened paper towels, on a microwave-safe plate and cook in a microwave oven at high power (100 percent) until tortillas are hot, about 1 1/2 minutes.
06Holding knife at a 45-degree angle, thinly slice steak across the grain. Serve with tortillas, avocado, romaine, and cilantro.