From Wikipedia, the free encyclopedia
A hanger steak is a tender cut of beef steak which is said to "hang" from the diaphragm of the steer. (The diaphragm itself is a tougher muscle, comprising the outer skirt steak.) The hanger is attached to the last rib and the kidney. It resembles flank steak, but is a vaguely V-shaped pair of muscles with a long, inedible membrane down the middle. The hanger steak is very tender, but has an intense flavor, and is best marinated and cooked quickly over high heat (grilled or broiled) and served rare or medium-rare, to avoid toughness.
Raw
Raw Hanger Steak
There is only one hanger steak per animal, and the entire cut typically weighs about 1 to 1.5 lbs (450 to 675g). It is prized for its tenderness and flavor, and was sometimes known as "butcher's steak" because butchers would often keep it for themselves rather than offer it for sale.

The hanger steak has traditionally been most popular in Europe. In French, it is known as the onglet, in Italian the lombatello, and in Spanish the solomillo de pulmon. In the United States, it has only recently become popular; formerly, it was not separated as an individual cut.  It is also known as the "hanging tender", and occasionally is seen on menus as a "bistro steak".
Cooked
Cooked Hanger Steak