Do you have a roasting rack?

I season lightly (no salt) , place the meat on the roasting rack fat side up and put about 1 to 1 1/2 cups of water in the bottom of the pan. Not enough so it touches the meat, but the water will give the oven a moist environment.

Set the oven for 325, forget it till about half way thru the cooking process, than start basting the meat with butter and seasonings till it is done. I use a convection oven so I cook about 20 min per lb. I'm not sure how long it would take in a conventional oven.

****OR***

Use indirect heat on your charcoal grill and follow the above instructions.

Did a prime rib last weekend on the grill and it was GREAT.

Good luck!