Flank steak may not be the most tender cut of meat you'll ever eat, but it could be the tastiest. And it's often a good bargain.

The flank is a long, flat and fibrous muscle, so it needs to be either seared and served moderately rare or braised until tender.Either way, carving this steak into thin slices across the grain at a 45 degree angle makes for a more pleasant bite.The flank is thin and boneless (with almost no waste), so it's a perfect candidate for marinades, which will penetrate well.This ginger-soy marinated flank steak can be grilled and enjoyed on its own or turned into this Asian-inspired sandwich by surrounding it with crunchy toasts, sweet and spicy mayo and a generous handful of peppery, fresh watercress.Marinate the steak in the morning for a quick and delicious supper from the grill.Ginger-SoyMarinated Flank Steak SandwichesStart to finish: 30 minutes (plus 2 to 24 hours marinating time)Servings: 4For the marinade:2 tablespoons rice vinegar2 tablespoons light brown sugar2 tablespoons reduced-sodium soy sauce2 tablespoons canola oilcup grated fresh ginger2 teaspoons chili-garlic sauce, or more to taste4 scallions, ends trimmed and thinly sliced1 pounds flank steakFor the sandwich spread:cup reduced-fat mayonnaise1 tablespoon honey2 teaspoons chili-garlic sauceFor the sandwiches:Eight -inch-thick slices crusty country-style bread1 tablespoon extra-virgin oil3 cups loosely packed watercress or arugulaIn a small bowl, whisk together the vinegar, brown sugar and soy sauce until the sugar is dissolved. Whisk in the oil, ginger, chili-garlic sauce and scallions.Place the steak in a shallow glass dish. Add the marinade and turn to coat the meat well on both sides. Cover and refrigerate for at least 2 hours and up to 24 hours, turning once.Heat a gas grill to medium-high or light a charcoal fire.Meanwhile, in a small bowl, stir together the mayonnaise, honey and chili-garlic sauce. Set aside.Brush both sides of the bread slices lightly with olive oil.Grill the steak until the underside is well browned, about 5 minutes. Turn the steak over and grill about 4 minutes longer for medium-rare.While the steak is grilling, place the bread slices around it to toast, about 1 minute per side.Let the steak stand for 5 minutes, then cut it across the grain into thin slices. Spread a thin layer of the chili-garlic mayonnaise on each toasted bread slice. Arrange the steak over 4 of the slices.Top with watercress or arugula and the remaining bread slices.Nutrition information per serving (values are rounded to the nearest whole number): 520 calories; 174 calories from fat; 19 g fat (6 g saturated; 0 g trans fats); 58 mg cholesterol; 47 g carbohydrate; 37 g protein; 2 g fiber; 780 mg sodium.