To prepare the brisket:
1. Trim your brisket. (Remove the membrane from the meat, and any excess fat.)
2. Place the brisket, fat side up, in an aluminum baking pan. Inject it by eyeballing 1-inch squares all over the brisket and injecting half of the beef injection in those squares. Flip the brisket over, fat side down, and pour the remaining injection/marinade over the meat. Cover and refrigerate for at least 6 hours.
3. Thirty minutes before you are ready to cook the brisket, heat smoker to 350 degrees F. (You can also use a gas grill, but you'll need to put your wood chips on one side that has the flame lit and the meat on the other that is unlit.)
4. Remove the brisket from the marinade and discard the marinade. Using your hands, apply the beef rub all over the meat. Place the brisket in a clean aluminum baking pan, place the pan in the smoker, and cook for 2 1/2 hours.
5. Remove the pan from the smoker and cover it with aluminum foil. Put it back into the smoker and cook for another 1 1/2 hours or until the temperature in the point end of the meat reaches 205 degrees F.
6. Remove the pan from the smoker and wrap the pan, still covered with aluminum foil, in a thick blanket. Let it rest at room temperature for 3 to 4 hours.
7. Unwrap the pan, discard the foil, and remove the brisket, taking care to save the accumulated juices. Set the brisket aside. Strain the juices of all grease, and pour the juices into a medium saucepan. Warm the juices over medium heat, and allow them to come to a simmer. Meanwhile, slice the brisket against the grain; try to make the slices as consistently sized as possible. Place the slices on a warm platter and pour the juices over them. Serve immediately.
To make the beef rub:
In a large bowl, combine all the ingredients thoroughly. You can store this rub in an airtight container indefinitely.
To prepare the beef injection and marinade:
In a large stockpot over high heat, bring the water to a boil. Add the beef base and the beef au jus to the water, and stir until dissolved. Remove from the heat. If reserving for a later use, let the liquid cool; then pour it into a jug or bottle. It can be stored in the refrigerator for up to 2 weeks.