First, we are going to want to marinade our pork tenderloin. You can use your favorite marinade; just avoid marinades high in salt as they will absorb a lot of moisture. If you don't have any marinade, feel free to use Italian dressing. Allow the tenderloin to marinade for at least an hour to absorb the flavor.
Next, preheat your gas grill to its hottest setting. Place your tenderloins on the grill and allow the grill to sear to the outside of the meat. Once the first side is seared, rotate it and sear each portion until the meat has grill lines all the way around.
Next, lower the temperature on your grill to the low to medium setting. We are going to remove the meat until the grill cools down, then place it back on the grill and allow the meat to slow cook. By searing the outside, you are sealing the juices inside, and then slow cooking the meat to prevent the outside from burning while maintaining a juicy center.
Pay close attention to your meat, every 5 minutes, stick a meat thermometer into the thickest piece of the pork. If you want the meat to be medium rare, remove the tenderloin at 145 degrees F, medium at 160 degrees F, or 170 degrees F for well done.
Allow your freshly removed pork tenderloin to sit for 10 minutes, season, and enjoy your meat fresh off the grill!