Part 5/8:
While the prime rib is resting, I'm going to make a simple au jus to go with it. I've scraped all the grease and little bits from the roasting pan into a skillet, and it's nice and hot. I add a little bit of flour, just to give the au jus a little bit of body without making it too thick like a gravy. After cooking the roux for a couple of minutes, I whisk in the beef stock, season it with salt and pepper, and let it heat up.