This was only my second attempt at Prime Rib. This recipe is a keeper. I couldn't find prepared hot mustard, so I used sweet hot mustard. It was a little runny so the salt didn't stay on the sides very well. I also altered the baking time, 1 hour at 450, then I turned down the temp to 350 till the core temp was 120. After resting for a few minutes, the rost was a perfect medium rare. So, our Christmas dinner prime rib was tender and flavourful. Great recipe, thanks!