Broiled Flank-Steak Sandwiches
Make horseradish sauce: In a small bowl, whisk together sour cream, mayonnaise, horseradish, and mustard. Season with salt and pepper. Cover with plastic wrap; refrigerate while preparing steak.Advertisement
Heat broiler, with rack 6 inches from heat. Season steak well on both sides with salt and pepper; rub with 2 tablespoons oil. Place on a roasting pan fitted with a rack. Broil 6 minutes on each side for medium-rare. Let rest 5 minutes before slicing 1/4 inch thick.
Place watercress in a bowl; toss with remaining tablespoon oil and the lemon juice. Season with salt and pepper. Serve on toasted bread, topped with steak, horseradish sauce, and roasted peppers.