¼teaspoonliquid smokeoptional - if finishing in oven
Set sous vide to 155-degrees.
Combine pepper, salt, and pink salt (if using) in a small bowl. Sprinkle brisket with ⅔ of mixture and rub to coat. Reserve the remaining spice mixture for finishing.
Add the brisket to a vacuum bag and add liquid smoke (if finishing in the oven - not needed if finishing on the smoker or grill). If needed you can cut the brisket into 2-3 pieces so that it will fit into your bags. Seal.
Place the bag(s) in the water bath, making sure not to block the intake or output sections of the sous vide, and cook for 24-36 hours.
Remove brisket from water bath and place in a bowl of ice water for 30-45 minutes, until it reaches room temperature. (At this point, the brisket can be stored in the fridge for up to 1 week.)
Remove brisket from bag and place on a paper towel-lined plate. Pat it very dry with paper towels then season with the remaining spice mixture.
To Finish on the Grill:
Grill over indirect heat at a temperature of about 225-degrees for 3 hours.
To Finish on a Smoker:
Preheat smoker to 225-degrees. Add brisket and cook for 3 hours.
To Finish in the Oven:
Preheat oven to 275-degrees convection (or 300-degrees standard). Add brisket and cook for 2 - 2 1/2 hours.
Allow to rest 30 minutes. Then slice against the grain and serve.
You may need to double bag the brisket if the seal doesn't form properly. It's always a good idea to be on the safe side, especially with a long cook like this.