Delicate pork tenderloin is the extra lean meat adjacent to the loin. This tasty, supple little muscle has a tendency to dry out quickly during cooking and can go from perfectly pink to dry and mealy the second you turn your back on the sauté pan. Our solution to the tenderloin quandary is to provide it with a protective layer of much needed fat in the form of rich, salty pancetta. As the tenderloin roasts the pancetta crisps, basting the tenderloin with its fat, keeping the lean muscle moist and infusing it with the robust flavor of pancetta. —Toponia Miller
Season the tenderloin with sea salt and freshly ground pepper. In a small bowl, mix together the mustard and wine. Using a pastry brush or your hands, cover the tenderloin liberally with the mix. Sprinkle rosemary evenly over the roast.
Neatly cover a 10x10 inch (25 x 25 cm) square of waxed paper or parchment with the slices of pancetta so that they are overlapping one another by about a half-inch (1.25 cm). Lay the tenderloin one inch from the bottom of the sheet, parallel to the edge. Fold the bottom inch over the tenderloin, and then roll the paper around the tenderloin. The pancetta should be tightly wrapped around the tenderloin. Remove the paper.
Place the roast onto a rack fitted over a baking sheet or roasting pan and place in the middle of the oven. Roast for about twenty minutes or more until the pancetta is golden and crisp and a meat thermometer reads 140°degrees when inserted into the thickest part of your roast.
Remove from the oven and let rest for five to ten minutes. Slice into one-inch (2.5 cm) rounds.