Make a hole for stuffing that runs lengthwise through pork loin: Beginning in middle of 1 end of roast, insert a sharp long thin knife lengthwise toward center of loin, then repeat at opposite end of loin to complete incision running through middle. Open up incision with your fingers, working from both ends, to create a 1 1/2-inch wide opening, then pack with all of stuffing, pushing from both ends toward center. Pack it as tightly as possible.