Flat iron steak is a cut of beef that comes from the shoulder (or chuck) of the cow, specifically the top blade. The name "flat iron" is believed to come from the steak's shape, which somewhat resembles an old-fashioned flat iron. It's known for its rich flavor and tenderness, making it a popular choice for grilling and other cooking methods.

The flat iron steak is usually well-marbled, which contributes to its flavor and tenderness. However, it has a line of tough connective tissue running through the middle, which is typically removed by butchers to make the steak more palatable. This cut is praised for being relatively affordable compared to other premium cuts like ribeye or filet mignon.

It’s often used in recipes where a rich, beefy flavor is desired, and it's versatile enough to be cooked in various ways, including grilling, broiling, or pan-searing.