This video shows you how to make a delicious Dijon mustard pan sauce for Chef John’s Stuffed Pork Tenderloin. To create the foundation of the sauce, you’ll add mustard and stock to the roasting pan, scraping the meaty bits and juices off the bottom. You'll reduce the stock and finish by swirling in a little cold butter. Watch the video, then get Chef John’s recipe for Dijon Pan Sauce. It’s super easy, and you can make it while your roast rests.