Best way to reheat Prime Rib?

I have wonderful prime rib leftover from Christmas that I currently have in the freezer along with about 1/4 cup of the au jus. The piece of beef is about 2 1/2 inches thick and includes both one end cut and then the rest up to the wonderfully rare center. What would be the best way to reheat this, yet retain it as rare as possible?

Heat the au jus then place the rib in the hot sauce for a short amount of time. It will warm it but not cook it more and will help keep it very moist. Thats how they do it in restaurants.