A good recipe for barbecue pork tenderloin is to place the pork into a slow cooker with 1 12-ounce can of root beer. Cook the pork on low for six to seven hours, until the meat shreds easily. Remove the pork from the slow cooker, and shred with a fork. Drain the root beer from the slow cooker. Return the meat to the slow cooker, and add 1 12-ounce bottle of barbecue sauce. Stir to cover the pork with sauce.
To make a pork tenderloin in the oven, preheat the oven to 350 degrees Fahrenheit. In a small bowl, combine 1/2 teaspoon each of salt, pepper and garlic powder. Rub the seasonings into the pork tenderloin, and place it into a roasting pan.
Chop 1 stalk of celery, and thinly slice 1/2 of an onion. Place the vegetables on top of the pork. Cover the pork and vegetables with 2 cups of red wine, and bake for 45 minutes. Remove the meat and vegetables from the roasting pan, and place on a serving platter.
Add 1 packet of dry brown gravy mix to the roasting pan, and blend it with the wine and cooking juices. Stir the gravy until it thickens. Slice the pork tenderloin, and cover it with the gravy.