Flank Steak The long triangular-shaped muscle from the fibrous underside of a flank of beef.  A traditional preparation is marinated, broiled rare and sliced thin against the grain of the beef.  Flank steaks have a beefy flavor, but they are substantially tougher.  Thus they are generally marinated or cooked using a moist method such as braising.  It also can be rolled and stuffed, then baked in the over or cooked in a crock pot.