Set sous vide to 180° Fahrenheit.
Heat skillet over medium heat. Add IPA beer to Skillet. and simmer until all alcohol is evaporated. about 10-15min
Rub spices and mustard on the fat side of corned beef.
Transfer corned beef, IPA beer, beef stock, garlic, and onion to a bag. Remove air using either a vacuum sealer or the displacement method.
Drop bag in sous vide and cook for 10 hours.
Remove corned beef from bath and bag, saving liquid and onions from the bag. Transfer corned beef to a skillet warmed over medium heat. Sear 1-2 minutes per side then set aside to rest.
