Method:
For the rub, combine brown sugar, chili powder, paprika, salt, pepper and coffee in a medium bowl. Stir to combine well.
Preheat oven to 275°F. Rub the brisket all over with coffee rub and set aside for 30 minutes. Store leftover coffee rub in an airtight container at room temperature. Arrange carrots and onions in the bottom of a roasting pan. Set brisket on top of vegetables. Pour beer over brisket and roast, 3 to 5 hours, until brisket is tender and falling apart. Allow about 45 minutes per pound of brisket. When the brisket is done, you should be able to separate the meat into shreds easily with a fork. Remove meat from roasting pan and let rest 10 to 15 minutes.
Pour the pan juices and vegetables into a saucepan. Skim the fat off the top of the juices and discard. Slice meat across the grain and arrange on a platter. Serve juices and vegetables with meat.