A 1" thick beef steak cut from the abdominal muscles. Cuts from this area are lean, very flavorful, and best when braised, or marinated and grilled. Serve rare.A relatively long and flat cut, flank steak is used in a variety of dishes including London Broil and as an alternative to the traditional skirt steak in fajitas. It is best when marinated for increased tenderness. Because it comes from a strong, well-exercised part of the cow, it should be sliced across the grain before serving to maximize tenderness. U.S. raised grass-fed beef.