Prepare UDS barrel style pit or another indirect smoker for cooking at 275 degrees F (140 degrees C). Add 2 chunks of hickory wood for smoke flavor.
Remove Whole Beef Brisket (15 pound) from packaging, remove silver skin from meat side and trim fat to 1/4-inch so the brisket lays flat on cutting surface.
For the Mexican Seasoning, combine Chili Powder (1 tablespoon), Ground Cumin (1 tablespoon), Granulated Garlic (1 tablespoon), Paprika (1 tablespoon), Onion Powder (1 tablespoon), Salt (1 tablespoon), Fresh Oregano (1 teaspoon), Chipotle Chili Powder (1 teaspoon), Ancho Chili Powder (1 teaspoon) and Cayenne Pepper (1/2 teaspoon).
Season both sides of the brisket with Killer Hogs The A.P. Rub (1/4 cup) and the Mexican Seasoning.
Place brisket on pit and smoke for 3 hours, or until the color of the brisket starts to turn dark.
For the Brisket Jus, melt Butter (1 tablespoon) over medium heat and add White Onion (1) and Garlic (4 clove). Cook just long enough to sweat the onions then add Chipotle Peppers in Adobo Sauce (4). Use a wooden spoon to break up the peppers, then add Beef Broth (16 fluid ounce) and Dark Beer (8 fluid ounce).
Simmer for 5 minutes but don’t bring the Brisket Jus to boil.
Place the brisket in a full size aluminum pan and pour in Brisket Jus. Insert a probe thermometer into thickest part of the flat and cover pan with foil. Continue to cook until internal temperature reaches 204 degrees F.
Remove brisket from pit, vent the steam from the pan, and rest in a dry cooler for at least 2 hours.
Separate the flat and point. Slice flat across the grain into 1/4-inch slices. Shred the point end of the brisket by hand. Reserve the Brisket Jus for added moisture if desired.
For the tacos, warm White Corn Tortilla (1 package) on the grill or oven.
Top each tortilla with a slice of brisket or with shredded point.
Add Fresh Cilantro (1 pinch), Pickled Red Onions (1 pinch), White Onion (1 pinch), Avocado (1 slice), and Lime (to taste).
To make Avocado Crema, combine Sour Cream (3/4 cup), Avocado (2), Chipotle Pepper (1), Garlic (3 clove), Lime (1/2), and Salt (1/2 teaspoon). Drizzle Avocado Crema on top of tacos. Serve and enjoy!