Plan ahead! This recipe requires overnight time. Start the Traeger grill on Smoke with the lid open for 4-5 minutes to establish the fire. While waiting, season the brisket on all sides with Prime Rib Rub (reserve 1/2 tablespoon of the seasoning for later use). Place the brisket on the grill grate, close the lid, and leave on Smoke for 2 hours
After the brisket has smoked for 2 hours, remove to a large sheet of plastic wrap. Tightly wrap the brisket (we used 3 pieces of plastic wrap to esnure a tight seal) and place in the refrigerator overnight. The time spend in the fridge will intensify the smoky flavor.
The next day, open the lid and start the Traeger on Smoke for 4-5 minutes to establish the fire. Close the lid, turn the temperature setting to High and allow the grill to preheat for 10-15 minutes. Unwrap the brisket and place it fat side up on the grill grate. Grill for 8-10 minutes per side, or until the brisket has developed nice grill marks on each side.
Meanwhile, preheat a large skillet or dutch oven over high heat. Cook the bacon until golden brown and crisp.
Add the diced onions to the pan and cook until tender (about 6 minutes) then add the garlic and cook an additional 2 minutes.
Stir in the tomatoes, chili sauce (or ketchup), brown sugar, beef stock, and the remaining 1/2 tablespoon of Prime Rib Rub. Bring to a simmer.
When the brisket has finished searing on both sides, place it fat side up in a large dutch oven or baking dish and pour the hot sauce directly on top. Turn the temperature setting on the grill down to 350 degrees.
Cover the dish with a lid or tin foil and place directly on the grill. Close the lid and cook for 1 1/2 hours. The liquid will have decreased by about half. Pour in the beer to bring the liquid back above the brisket. Put the lid back on and return to the grill for an additional 1 1/2 hours or until the brisket has reached an internal temperature of 203 degrees.
Remove the brisket from the baking dish to a cutting board and allow it to rest for at least 15 minutes. While the brisket rests, add the cider vinegar and pan juices to a pan. Bring the sauce to a boil until it reduced to a thick BBQ Sauce consistency. You may need to separate any excess bacon fat from the top with a spoon.
Slice the brisket thinly and drizzle with the warm BBQ sauce. Serve immediately and enjoy!