Preheat the oven to 400 degrees. Brush a 1½-pound pork tenderloin with 2 tablespoons cup rhubarb sauce
and sprinkle with ⅛ teaspoon kosher salt and ⅛ teaspoon freshly ground black pepper. Roast the tenderloin, brushing with an additional 2 tablespoons sauce after 10 minutes, until the internal temperature reaches 150 degrees, 20 to 25 minutes total. Let rest 10 minutes before serving with additional rhubarb sauce on the side.