|Prime rib beef||5 Pound|
|Onion soup mix||1 1⁄2 Ounce (1 Package)|
|Mushrooms||1 Dozen, sliced|
Place roast on cooking platter and rub with soup mix.
Arrange roast fat side down, with mushrooms over top and around sides.
Cook uncovered on High for 10 minutes.
Remove roast from microwave, turn on one side and let stand 5 minutes (standing time permits microwaves to penetrate to center of roast).
Return to microwave and cook 5 minutes.
Remove from microwave, turn on other side, and let stand 5 minutes.
Return to microwave for 5 more minutes.
Turn roast again, let stand 5 minutes, and return to microwave.
For medium rare, cook until microwave meat thermometer registers 125° to 130°, about 10 minutes more (roast will continue cooking after it is removed from microwave).
Allow the roast to rest before carving.
This is important, since it allows the juices to be redistributed throughout the roast.
lf your microwave has a Medium or Roast setting, eliminate standing time between turnings, and, instead of cooking on High for the last 10 minutes, cook on Roast or Medium for about 20 minutes (check internal temperature after 10 minutes).
The slower cooking in the final stage will permit microwaves to penetrate to center of roast, eliminating need for standing time in the earlier stage.