The best way to heat precooked prime rib is to cook it in an oven on low temperature settings for a few hours, until an internal temperature of at least 135 degrees Fahrenheit is reached. Precooked prime rib can be from leftovers or purchased at a convenience food.
For packaged precooked prime rib, follow a couple of steps to get the meat up to temperature.
- Preheat the over and prepare the prime rib Preheat the oven to 300 F. Remove the prime rib slices or roast from its packaging and rewrap in aluminum foil.
- Cook to desired doneness Place the prime rib and cook for at least 2 1/2 hours. For medium-rare prime rib, remove from the oven once the meat reaches 135 F, using a meat thermometer.