This is one of the easiest cuts you can roast. There are many ways, here is our simple favourite.
Take your prime rib out of the fridge 15min/Kg ahead of going into the oven. find your favourite steak seasoning and apply it generously. Your prime rib has already had the bones cut and tied back on so it will be easy to cut once roasted.
Preheat your oven to 450F/235C
put your roast in the roasting pan with at least a 2"/50mm lip. an aluminum foil pan comes in handy if yours are too shallow. Insert your probe or oven safe thermometer.
place your roast in the oven for about 15-20 min then turn the temperature down to 375F/190C. Estimated time will be about 40min/Kg at this time check your thermometer. temperatures to aim for are listed below. Always take the roast out 4-5deg F before it is finished. remove it from the oven place it on the cutting board and leave covered for 10min/Kg
After removing the roast from the pan, scrape off what is left behind into a pot and separate the fat. Wisk some corn starch to your beef stock and stir it into the drippings on the stove over a simmering heat. Reduce the sauce to a gravy. remember that it will always thicken up once removed from the pot.
Cut the strings from your roast and remove the bones. Slice to desired thickness.