Skirt steak

 
Skirt steak is a cut of beef steak from the plate. It is long, flat, and prized for its flavor rather than tenderness. It is not to be confused with flank steak, a generally similar adjacent cut nearer the animal's rear quarter.
Characteristics.
Both the inside and outside skirt steak are the trimmed, boneless portion of the diaphragm muscle attached to the 6th through 12th ribs on the underside of the short plate. This steak is covered in a tough membrane that should be removed before cooking.
The inside skirt steak is often confused with the flank steak, which is the tail of the porter house and T-bone steaks of the short loin found on the flank. It has similar cooking properties.
In the United States, the North American Meat Processors Association (NAMP) classifies all skirts steaks NAMP 121. NAMP 121 is further subdivided into the outer (outside) skirt steak (NAMP 121C) and the inner (inside) skirt steak (NAMP 121D). The beef flank steak (NAMP 193) is adjacent to the skirt, nearer the animal's rear quarter.
History.
The name "skirt steak" for the butcher's cut of beef diaphragm has been in use since at least the 19th century. The cut is defined as extending to the 10th rib in the early 20th century. It was formerly considered a less commercially mass-salable cut in America, hence its use for "fajitas" by the vaqueros in Texas. By the 1980s the popularity of the dish was driving the price of the cut beyond the affordable price range for middle-class Hispanics who invented it.
The U.S. Food Safety and Quality Service established in 1977 (now the Food Safety and Inspection Service) by the Department of Agriculture (USDA) had designated the cut as "beef skirt diaphragm" (with the adjoining cut being called "hanging tender diaphragm"). But the diaphragms were treated as "offal" rather than meat by the Japanese government, thus exempt from any beef import quota restrictions. These cuts of U. S. beef (and Canadian beef) could consequently be exported to Japan without quota restrictions, and constituted a major portion of the U.S. beef trades there from ca. 1975 into the 1980s, until the beef import deregulation in Japan lifted the quotas in 1991.
Uses.
Skirt steak is the cut of choice for making fajitas, arrachera, Chinese stir-fry, churrasco, and in Cornish pasties.
To minimize toughness and add flavor, skirt steaks are often marinated before grilling, pan-seared very quickly or cooked very slowly, typically braised. They are typically sliced against the grain before serving to maximize tenderness.