They had prime rib on sale and I bought my first one to try on the smoker tomorrow. A five pounder. I have got a pretty good idea on how to cook the prime rib since I have done a roast before and it turned out very well. I also picked up the makin's for Chef JJ's au jus and had a few questions about the au jus. What's the best way to thicken the au jus if I wanted to do that? I was thinking that some mushrooms would be good cooked in the au jus. Has any one tried that? Is it better to smoke the meat on a rack over the au jus pan or could I lay the roast, rib side down, in the pan with the au jus.