Liberally season the rib roast with kosher salt, pepper, and garlic powder so everything is well coated.
Place the roast in a vacuum seal bag or zipper bag and place garlic and rosemary on each side of the roast. Vacuum seal the bag and place in a sous vide container.
Refer to your sous vide guide to determine cooking times and temps. For medium rare set sous vide cooker at 132 degrees and cook for 4+ hours.
Remove the roast from the bag and prepare to sear. Save the contents from the bag and add it to a pot with beef stock. Simmer and reduce to make an au jus.
Sear the roast for 60 seconds on each side or until a crust has developed on each side.