A hanger steak is a cut of beef steak prized for its flavor. Hanger steak resembles flank steak in texture and flavor. It is a vaguely V-shaped pair of muscles with a long, inedible membrane down the middle. The hanger steak is usually the tenderest cut on an animal and is best marinated and cooked quickly over high heat (grilled or broiled) and served rare or medium rare, to avoid toughness. So why don't you see hangers more often if they are full of flavor and tender? Because there's only 1 per animal! Learn more on what the cut is and how to cook it here.
Be sure to cut against the muscle grain - the muscle grain on this great steak runs at a 45 degree angle, rather than the end-to-end like usual, so take care when slicing!