Wrapping a boneless pork loin (or any large cut of meat) with string before roasting gives the meat a uniform shape to ensure even cooking. When the meat in question is stuffed, the string also keeps the filling in place.
1. Without cutting kitchen string from its roll, slide a section under the end of the loin closest to you. Pull the string around crosswise and tie the first knot, leaving a long end to tie the second knot.
2. Make a large loop on your hand and slide it around the opposite end of the loin, stopping one inch below the first loop. Pull down on the string to tighten it. Continue making loops at 1" intervals until the entire loin is covered.
3. Wrap the string under the loin once, making a loop lengthwise. Tie the second knot to the end of the first one and cut the string.