- Preheat. Preheat your smoker to 275 degrees F using your favorite hardwood. My preferred combination for brisket is an equal mix of oak and cherry.  
- Trim the brisket flat. Use a sharp knife to trim off most of the fat cap from the top of the brisket and all of the silver skin from the underside of the brisket. 
- Inject the liquid into the meat. In a jar, combine the beef stock and the Worcestershire sauce. Use a meat injector to distribute the injection every 2-3 inches throughout the brisket flat. 
- Season. Sprinkle Hey Grill Hey Beef Rub equally across all sides of the brisket flat. 
- Smoke the brisket flat. Place the brisket flat on the smoker, close the lid, and cook for 4-5 hours, or until the internal temperature of the meat reaches 165 degrees F. 
- Wrap. Remove the meat to a large sheet of butcher paper. Drizzle the brisket flat with 1/4 cup of melted beef tallow and wrap tightly, tucking as you wrap to ensure there are no big air pockets or exposed pieces of brisket. 
- Continue smoking. Return your wrapped brisket flat to the smoker, close the lid, and continue smoking at 275 degrees F for about 2-3 hours, or until the meat is very tender. The thermometer probe should slide in and out like it's softened butter and will likely read around 200 degrees F. 
- Rest. Remove the smoked brisket flat from the smoker to a baking sheet and allow it to rest for at least 45 minutes or up to an hour. 
- Slice and serve. Once the meat is well rested, open up the paper and slice against the grain. I like to shoot for slices that are about 1/4 inch thick. Serve with BBQ sauce, pickles, peppers, and other tasty sides.