Preheat the oven 475°F.
Butterflying a tenderloin: Trim the silver skin or connective tissue with a very sharp, thin knife. Place the tenderloin on a cutting board vertically then slice through the tenderloin about a 1/3 of the way down the side. Fold that flap open and give it a light pounding using a mallet or the back of a small saute pan. Turn the cutting board 180 degrees and slice into the tenderloin 2/3 of the way down on the other side so that it opens up like an accordion or a business letter. Give that side a light pounding, so that the whole tenderloin is flat, rectangular and ready to be stuffed and rolled up. Repeat with other tenderloin.