Place meat in shallow roasting pan uncovered
Turn oven on 325 degrees
Roast rare: 12-13 min per pound (8 lb = 104 min OR 1 hr 44 min)
Add the Mirepoix during the last 44 min
Take out of oven at:
RARE: 120 degrees
MEDIUM RARE: 125-130 degrees
let set for 25-30 min (meat will raise another 5-10 degrees while setting)
For 8 lbs of prime rib:
6 cloves garlic (crushed)
1 teaspoon salt
1 teaspoon pepper
1 teaspoon herb leaves (tarragon, rosemary, thyme, etc)
1/2 cup onions (finely chopped)
1/2 cup carrots (finely chopped)
1/2 cup celery (finely chopped)
Sauté in butter until just starts to soften, then add wine or broth and boil briefly