Place brisket into a large pot. Sprinkle one spice packet over top. Pour in beer, then add enough water to cover briskets by 1 inch. Add peppercorns, garlic, and bay leaves, cover, and bring to a boil.
Reduce the heat to medium-low. Keep covered and simmer, checking hourly and adding more water if necessary, until meat is tender and can be easily pulled apart with a fork, 4 - 5hours
Transfer brisket to a cutting board; let rest until they firm up a bit, about 10 minutes. Slice or shred meat, then place onto a platter for serving.
Cut up veggies how you'd like them. Place in cooking liquid and bring to a boil. Boil until fork tender, about 20 - 30 minutes.