To make the brine, combine water, Kosher salt, pink curing salt, pickling spices and brown sugar in a large stock pot. Bring to a low boil, stirring to make sure the salt and sugar dissolve.
Remove and all to come to room temperture.
In a large plastic container, place cleaned brisket and cover with room temperture brine. Make sure the brisket is fully submerged in brine liquid. You might have too much brine, skim out spices and add to brisket, while discarding any leftover liquid.
Brine for 7-14 days in the refrigerator, making sure it is fully submerged each day.
When ready to cook, remove from brine, reserving pickling spices. Place into a roasting pan and preheat oven to 250 degrees.
Cover with 8 cups water and Guinness stout (optional). Cover with aluminum foil and braise for 1 hour or every pound of brisket.
About 45 minutes before serving, remove brisket from oven. Ladle out 80% of the liquid. Spread vegetables around the brisket and return to the oven, uncovered.
Remove and allow meat to rest for 10 minutes before slicing against the grain. You can return to the juices and toss before serving with vegetables.