I ran a kitchen for quite a few years when I was younger. I would make anywhere between 5 and 10 ribs a night. I personally love salty food so I would rub mine with all the salts in the cupboard, onion, garlic, celery and then salt and pepper the heck out of it too. You should try to get quite a thick coat of the salts applied ans rub it in well. We cooked all of ours in roasters pans not in the oven but I would assume it would all be the same. After salting well place the rib in your pan and then chop up semi fine and spread over your rib: a whole onion, 4 celery sticks. Next dump 2 cans of whole stewed tomatoes. Cover with lid or foil for baking.
Preheat over to 500°F
After 15 minutes on 500°F, reduce the heat to 325°F. To figure out the total cooking time, allow about 13-15 minutes per pound for rare and 15-17 minutes per pound for medium rare. The actual cooking time will depend on the shape of the roast and your particular oven. A flatter roast will cook more quickly than a thicker one. So make sure to use a meat thermometer. This is not a roast to “wing it”. Error on the rare side.
Roast in oven until thermometer registers 115°-120°F for rare or 125°-130°F for medium.
Keep it more on the rare side because you can cook it further in the AuJus before serving.
While the rib is cooking make up you AuJus. I like to start with at least a half gallon to a gallon because it will reduce with cooking as the night goes on and your guests will also be using it for dipping. Add beef base until you have the desired saltiness. You will probably be adding 1/4 cup per half gallon of water. It will become more salty as the AuJus reduces. I then add a touch of the onion and celery salt and four or five whole garlic cloves. If you are not a garlic fan leave them out. Bring this to a boil and then simmer until serving time.
Before serving dip the sliced portion of prime rib into the AuJus to warm or cook to the desired wellness. Place on plate and cover with a bit more AuJus.
You can also top the prime with the veggies you had in the roaster pan while it was cooking if so desired.
Enjoy. Let me know when I should be there!!