Combine dry rub ingredients. Generously apply dry rub to brisket. Allow brisket to marinate overnight, or a minimum of 8 hours. Rinse off dry rub under cold water. Dry completely with a towel. Sear all sides on a high heat grill and transfer to a smoker. Cook in smoker at a consistent ambient temperature of 250°, for 6 to 8 hours. After first 3 hours, baste with BBQ sauce every 45 minutes. Check for tenderness and desired doneness at hour 7. Adjust cooking time appropriately.
Tomatillo & Ancho Pepper BBQ sauce
Combine molasses, Coca Cola, Worcestershire sauce, red wine vinegar, and brown sugar. Set aside liquids.
Toss tomatillos in large bowl with oil, salt, and pepper. Char tomatillos on grill. Cool. Once cooled, put in blender, pulse, and puree until chunky. Set aside.
In a large pot on medium heat, combine oil and diced onion. Cook until golden brown and caramelized. Add garlic and cook for 2 minutes. Add spices and toast until fragrant. Add liquids, increase heat to medium-high, and reduce mixture by one half. Add tomatillos and ketchup, reduce heat to medium-low, and cook 1 hour until thickened.