Trim off excess fat from the brisket. Some fat will melt down while it bakes, but not the majority, so I like trimming it. There is a river of fat between the flat and the tip, trim most of the fat out, leaving it still connected by just an inch of meat.
Cover the entire brisket in mustard and then sprinkle the salt and pepper all over.
Place the brisket on a cookie sheet, cover with foil and place in the fridge until you are ready to smoke.
Turn your smoker on, let it smoke, then turn the temperature to 225.
Take the foil off the brisket, and place the meat on the smoker grill grates, fat side down.
Smoke for 6 hours.
Turn the heat up on the smoker to 250 and smoke another hour.
After 7 hours, remove the brisket and wrap it tightly in butcher paper, and place in a disposable pan. Place back on the smoker.
Turn the temperature back down to 225 and smoke another 5 hours.
Remove the brisket, keep the smoker on, go inside, carefully unwrap it, and slice the tip off of the flat by cutting that last inch of meat you left to keep it intact.
Wrap the flat back up, place it back in the pan, and cover the whole thing with aluminum foil to rest.
Chop the brisket tip into 1-inch cubes, place in a 9x13 disposable pan, and cover in your favorite BBQ sauce.
Place the uncovered pan full of brisket cubes back onto the smoker and smoke for an additional 60 minutes.
Remove and cover the burnt ends to keep warm while you slice the brisket flat that has been resting. Serve the burnt ends on the side of the brisket slices.