Clean away any membranes, fat or silver skin from the pork tenderloins. Slice tenderloin down the middle long way. Using a meat hammer, lightly pound the pork tenderloin. Then, rub with brown mustard.
Brush the grill with oil before placing the stuffed tenderloin on the grill. Place the pork seam side down and allow to grill for 7-10 minutes before turning.