For the layperson, it's often difficult to understand all the terms used for various cuts of beef. Traditional usage in various regions of the country can give the same name to very different cuts of meat, or different names to the same cut. Another potential source of confusion is the variance between a cut's food industry name and the name of the retail cuts that are derived from it. One prime example is the beef "knuckle," a large piece of beef from the hind quarters.
The "Primal" Cut
In the meat cutting profession carcasses are broken down, or fabricated, in two stages. The first is to divide the whole carcass into large wholesale portions, known as "primal" cuts. The second stage is to break each primal cut down further into retail cuts, such as steaks, roasts and stew meat. The knuckle, or sirloin tip as it's also known, is cut from a primal called the round, or hip of beef. As the name suggests, this is in the animal's hindquarters, and includes the hip with its related muscles, and a portion of the leg.
The Knuckle, or Sirloin Tip
The knuckle, or sirloin tip, is a portion of the larger round containing three distinct muscles. These are known to veterinarians as the rectus femoris, vastus lateralis and vastus intermedialis, or to meat shop customers as the tip center, tip side and tip bottom. All three are very lean, and are visibly separated from each other by seams of connective tissue.
Characteristics of Tip Center, Tip Side and Tip Bottom
The tip center is the tenderest portion of the round. It is a slightly flattened oval in cross-section, with a small seam of connective tissue visible in the middle. This does not need to be removed, as it will normally melt during cooking. The tip side is oblong, with a flat bottom and a gently rounded top. It contains no visible fat or connective tissue. The tip bottom is smaller and irregularly shaped, with a relatively large quantity of connective tissue visible.
Uses of The Knuckle, or Sirloin Tip
The knuckle can be used whole as a large roast, or can be cut up for stew meat or kebabs. If the knuckle is broken down further into its component muscles, they can be allocated to different purposes. The tip center makes a tender small roast, or can be cut into steaks tender enough for broiling or grilling. The tip side is also a useful roast, and can also be fabricated into steaks. These are not as tender as tip center steaks, and require tenderizing or marinating. The tip bottom is tough, and used for stew meat or ground beef.