Pork Tenderloin with Blueberry Barbecue Sauce

To make sauce: Combine ingredients in a medium saucepan. Bring to a boil over medium heat; reduce heat and simmer until thickened, about 45 minutes. Divide sauce between 2 bowls. Set aside. To make meat: Preheat grill to medium. Season pork with salt and pepper. Sear, turning to cook all sides, 10 to 15 minutes. Brush with half the barbecue sauce, turning frequently, until pork is thoroughly glazed, about 10 minutes more (a meat thermometer should read about 150 degrees). Set aside and let rest 5 minutes. Carve crosswise; serve with remaining barbecue sauce.