Trussing Basics

• There are many reasons for meats to be tied or "trussed." With poultry, it binds the legs and wings tightly to the bird for even cooking, and helps keep the shape attractive. With roasts and large cuts, tying the meat with twine can hold it together after the removal of bones, gristle or large seams of fat. Individual roasts or chops are sometimes tied with twine as well, either to hold them together -- as with roasts -- or to improve their shape. Only the last of these ordinarily applies to a tenderloin.

The Shapes of Things

• Tenderloins of beef, or of large game animals such as bison or elk, usually take the form of a slightly flattened cylinder that tapers and becomes flatter at one end. Through most of its length the tenderloin has a slightly oblong, rather than a round, cross-section. If it was truly cylindrical the tenderloin would cook more evenly, and butchers sometimes correct that by trussing the tenderloin at intervals along its length. When you later roast the tenderloin, you'll find it easier to achieve an even, perfect degree of doneness throughout its interior.

Tightening the Texture

• Texture provides a second reason for trussing tenderloin with twine. The tenderloin is a muscle that's used very little during the animal's life, which is why it's so tender. Some diners find that it's tender almost to a fault, having an oddly soft texture unlike most other steaks or roasts. By trussing it tightly at close intervals, the butcher can compact the tenderloin's texture slightly but noticeably. When you cook the tenderloin its proteins will set and become firm in that position, still tender but with a more agreeable firmness.

Bits and Pieces

• If your tenderloin isn't whole but in the form of medallions, there are two reasons for it to be cooked with the twine on. One is simply to ensure a better shape, just as if you were roasting a larger piece of tenderloin. The other is to combine two smaller pieces of the tenderloin into a single medallion. The tenderloin's tapered shape means that medallions cut from the thin end tend to be too light for a reasonable portion. Tying two of these smaller pieces together is a common technique in both restaurants and butcher shops.