
Set up the sous vide. Fill your sous vide container with water and set the immersion circulator to 129 degrees F for medium-rare (or your preferred temperature).
Season the prime rib. Pat the prime rib completely dry with paper towels. Combine the seasoning ingredients and coat the entire roast generously on all sides.
Vacuum seal. Place the seasoned prime rib in a vacuum-seal bag with the fresh rosemary. Vacuum seal the bag, removing as much air as possible.
Sous vide the prime rib. Submerge the sealed bag in the water bath and cook for 8 hours. Track temperature with a remote probe thermometer, if desired.
Sear the exterior. Remove the prime rib from the bag and pat it completely dry. Reserve any juices from the bag for making au jus if desired. (Searing options: 500 degree F grill: extra smoky charcoal flavor. Oven broiler: easiest, cleanest, nice browning on the exterior. Cast iron skillet: heaviest char and crunch on the exterior, makes your house smoky.)
Rest and slice. Let the prime rib rest for 10 minutes before slicing. Slice into 1 to 1 ½-inch thick slices and serve immediately.