- 1 (3 – 18LB) Prime rib roast (18LB was full rack, 7 ribs)
- onion powder
- garlic powder
- chopped garlic
- dried rosemary
- black pepper
- Preheat oven to lowest possible temperature setting, 150°F (66°C) or higher if necessary. (Some ovens cannot hold a temperature below 250°F/121°C.) Our oven's lowest temperature is 170°F
- Make a dry rub with salt, pepper, onion powder, garlic powder. Rub on meat.
- Place roast, with fat cap up in a large roasting pan.
- sprinkle chopped garlic and rosemary around meat.
- Add 1/2 cup water.
- Cover, place in oven and cook until center of roast registers 120-125°F (49-52°C) on an instant-read thermometer for rare, 130°F (54°C) for medium-rare, or 135°F (57°C) for medium to medium-well. In a 150°F oven, this will take around 5 1/2 to 6 1/2 hours; in a 250°F oven, this will take 3 1/2 to 4 hours.
- Remove roast from oven and tent loosely with aluminum foil. Place in a warm spot in the kitchen and allow to rest for at least 30 minutes and up to 1 1/2 hours. Meanwhile, preheat oven to highest possible temperature setting, 500 to 550°F (260 to 288°C).
- Ten minutes before guests are ready to be served, remove foil, place roast back in hot oven, and cook until well browned and crisp on the exterior, 6 to 10 minutes. Remove from oven, carve, and serve immediately.
- I like a minimum of 4 ribs which weighs ~ 10 lbs.
- The middle stays medium rare while the edges are medium.