One hour before starting to cook, season the roast with salt and pepper.
5 lb. Prime rib, Kosher salt, 1 Tablespoon Black pepper
Set up the Sous Vide machine to heat to a temperature of 132°F, and attach it to a very large pot of water. Place the roast in a plastic bag, then submerge it in the water completely.
Sous vide the meat for 6-10 hours, depending on the size of the roast. Remove from the bag, reserving the liquid, and pat the roast dry and let cool slightly.
Combine the softened butter, garlic powder, chopped herbs and pepper in a bowl, then use it to coat the top and sides of the roast. In the meanwhile, preheat the oven to 550°F.
Sear the beef in the oven for 8-10 minutes on a roasting pan with a rack, until the crust is golden.
Let the beef rest 15 minutes in aluminum foil, slice, and serve! Use the reserved liquid for Au Jus.
Au Jus Instructions
Add the liquids from the bag and the beef broth to a skillet and bring to a boil.
Prime rib drippings, 1 quart Beef broth
Reduce the heat and let simmer until reduced by half, skimming off any solids.
Serve poured over the prime rib or on the side to dip.
Notes
Prime ribs are large cuts of meat, so I suggest using a large soup pot or Dutch oven for the water bath. If the prime rib doesn't fit the container correctly and doesn't remain fully submerged, it won't cook evenly.
For the oven sear, make sure to set a wire rack on the pan so that the air can circulate under the beef as well.
Resting seems like something that can be skipped, but never skip resting beef! Make sure you tent the roast with foil and let it sit for 15 minutes. This ensures the meat is as juicy as possible.
Slice against the grain of the beef to ensure each slice is ultra tender.
It can be hard to remove all the air from the zip lock bag. I find it easiest to submerge all but the opening in water and zip it that way, then use a weight or clip to keep the bag submerged while cooking.