The flank steak is a beef steak cut from the belly muscles of the cow. Long and flat, the flank steak's best known application is London Broil — a misnomer, as the dish did not originate in London. The popularity of London Broil has driven up the price of flank steak over the past few decades, but it is still one of the most affordable steaks on the market. It is substantially tougher than the loin and rib steaks, therefore many flank recipes use marinades or moist cooking methods such as braising.The French are quite partial to this cut, known as "Bavette". It is quickly seared in a hot pan and eaten rare to maintain its tenderness. Strips of flank steak, known as arrachera, are very popular in Mexican cuisine and may be used to fill tacos, or served in large pieces as a main course. Flank steak used in Mexican cuisine may be tenderized by a marinade, or by mechanical tenderizing, using a machine similar to that used to produce cube steaks.Flank steak is best when it has a bright, red color. Because it comes from a strong, well-exercised part of the cow, it is best prepared when cut across the grain. Additional tenderness can be added by marinating the meat in a tenderizing liquid, including acids like tomato-based products, lemon juice, wine, vinegar, pineapple or ginger.Because the marinades in Asian cuisine tend to be tenderizing, flank steak is frequently used in this cuisine.In Chinese markets, the flank steak is often sold as "stir-fry beef" because it is how it is usually prepared. Most stir-fried beef dishes in Cantonese restaurants are prepared with this cut of beef.