I grew up on shoe leather for dinner on Sunday nights. My mother wasn’t particularly adept at cooking so for a very long time I only ate well done prime rib. Imagine when I discovered that it could be tender and succulent. Now, I cook my prime rib to rare and it’s rare from edge to edge losing the least amount of moisture during cooking.
First, you’ll need a thermometer. Here’s mine. I got it at Ikea, it was five dollars. You stick the probe in the centre of the roast and then the readout sits on the counter letting you know how things are coming along.
Next I take my roast and rub it with a mixture of horseradish, mustard, minced garlic, salt and pepper.
Then I cook it in a hot oven (450F) for around twenty minutes or until develops a brown crust.
Then I insert my probe thermometer and turn the oven down to it’s lowest setting. This is somewhere around 200F. Every oven will be different so this is where you’ll have to experiment with your own to determine how long it will take for your roast to reach 128 (for rare), 135 (for medium).
You remove your roast at a temperature that is lower than your final temperature because the roast continues to cook while it rests. Final temperature for rare is around 140F and for medium 150F. Most roasts will go up by around 15F during the resting period. The roasts that I use are very large and hold a lot of heat, they take around 3 hours total cooking time. Once your roast has reached the internal temperature that you have set, you let them rest for at least 30 minutes.
You’ll notice when you cut your roast that your desired doneness (rare, medium) is from edge to edge.