Flank steak and brisket have reputations as being tricky to cook, but they are among the most flavorful cuts of beef. Both come from the underside of the cow, with the brisket coming from the breast portion, while the flank is found closer to the belly, along the sides. Brisket works better for long, slow cooking methods, while flank steak does best with high-heat cooking.
Fat and Cartilage
Flank steak has little to no fat, unlike brisket, but both contain some sinew and cartilage. In many cases, this extra sinew on flank is removed by the butcher during processing, but sometimes, it is still attached. For brisket, the more marbling -- fat within the muscle -- it has, the more flavorful and tender the meat is after it is cooked. The exterior layer of fat, known as deckle, can be trimmed off almost entirely for a lower-fat brisket.
Flavor, Texture and Marinades
Both brisket and flank steak have a rich, beefy taste but have a reputation of being quite tough unless properly prepared. Marinating the meat prior to cooking -- regardless of method -- will help tenderize the steak. Because of their naturally strong flavor, both brisket and flank can withstand strong seasonings, with pepper, garlic, cumin and lemon or lime juice being common marinade ingredients. In the case of flank steaks that are cooked quickly, the marinade helps to tenderize the meat, making it easier to eat.
Bone or No Bone
Flank steaks never come with an attached bone, but brisket is sometimes sold bone-in. Bone brisket is best suited for slow smoking, where the long cooking time gives the bone time to add extra flavor to the meat. In some cases, flanken, a different name for short ribs, are mistaken for flank steak, as flanken comes from a similar area as flank steak.
Different Cooking Methods Needed
Since brisket takes best to slow cooking, it is most commonly cooked as one large piece. The low heat and long cooking times help break down the cartilage and melt the fat, retaining the meat's moist and adding extra flavor. Because of the low natural fat content, flank steak does best when it is cooked quickly, such as over a very hot grill. For both brisket and flank steak, slice thinly -- across the grain -- for a tender, toothsome meat.