There is no question that the hanger steak is my favorite cut of meat. I discovered it a number of years ago and have kept it in my back pocket to wow dinner party guests. The texture and flavor of the hanger is unlike any other cut of meat. It is just as flavorful as a ribeye but significantly less expensive. It's not commonly available in a lot of markets, so you'll need to track down your own source (I'm not giving mine up, cause I don't want to be fighting to get my meat). Check out the wiki on hanger for a solid description:
A hanger steak is a cut of beef steak which is said to "hang" from the diaphragm of the steer. (Anatomically the diaphragm is one muscle, but it is commonly cut into two separate cuts of meat: the "hanger steak" traditionally considered more flavorful due to its proximity to the kidneys, and the outer skirt steak which is composed of tougher muscle within the diaphragm.) The hanger is attached to the last rib and the spine near the kidneys. It resembles flank steak, and is a vaguely V-shaped pair of muscles with a long, inedible membrane down the middle. The hanger steak is not particularly tender, but has a lot of flavor, and is best marinated and cooked quickly over high heat (grilled or broiled) and served rare or medium-rare, to avoid toughness. Chefs with experience preparing beef kidneys report that the hanger steak's aroma preserves a trace of kidney.
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 flavor, and was sometimes known as "butcher's steak" because butchers would often keep it for themselves rather than offer it for sale.
There area a million marinades that would work for a hanger. It really grabs flavor. If you don't have time, a dry rub will also work well - I love my lavender salt or just a mix of garlic, onion, salt and pepper would work. Fresh herbs make a great rub as well. I'll often take a bunch of rosemary, thyme, some garlic and onions and wrap the meat up overnight. Get your grill really hot (charcoal is ALWAYS preferred) and turn four times, about 3-4 minutes each time to get char on the whole steak. Use your thumb to check doneness - it should be about as dense as the palm of your hand, underneath your pinky. The crust should be glistening.
To avoid dryness, the trick is to take the meat off the grill and wrap it in foil tightly for 10 minutes to rest. Then slice it with the grain widthwise into medallions (don't cut it on the diagonal like flank steak or it will be tough). Drizzle some olive oil or butter on the meat and pour the juices that accumulated in the foil. Sprinkle some granular salt and hit it with a shot of pepper.
Hangers do very well at parties, family style. Serve up a few with some cherry tomatoes and watch people ignore their utensils - finger food at its best. Don't forget to invite me.