Oil change: Avocado oil is excellent for roasting because it has a very high smoke point, and it's healthier than vegetable oil.
Make glaze: Stir together cranberries, cranberry juice, wine, syrup, thyme, mustard, salt, and pepper in a medium saucepan; bring to a boil over medium-high heat. Cook, mashing cranberries with a potato masher, until reduced to 1 cup, about 25 minutes. Remove pan from heat: add butter and stir until melted and combined. Stir in vinegar.
Make pork: Preheat oven to 500°F; brush a roasting pan with avocado oil. Sprinkle salt and pepper evenly over pork. Place in pan and roast for 15 minutes. Turn over and brush each tenderloin with 1/4 cup glaze. Cook until a thermometer inserted into the thickest portion registers 145°F, about 5 minutes or more, or to desired degree of doneness. Remove from the oven and let stand for 5 minutes before slicing. Serve with remaining glaze.