Preheat the oven to 425 °F (220 °C). To make cleanup easier, line a large baking sheet with sides or a jelly roll pan with parchment paper or foil. Place aside.

Remove extra fat from the brisket and rinse and pat dry. If your brisket is very lengthy, cut it in half to fit in your slow cooker.

In a medium mixing bowl, combine the spice rub ingredients. 1 tablespoon spice rub removed and placed in a medium dish for use in barbecue sauce Rub the remaining spice rub evenly over the meat before placing it on the prepared baking sheet. (If preferred, leave at room temperature for 30 minutes or refrigerate for up to 24 hours.) To sear the beef, bake uncovered at 425°F for 30 minutes.

Meanwhile, mix together all of the barbecue sauce ingredients including the 1 tablespoon reserved spice rub. Add 1/2 cup barbecue sauce, 1 cup water, 2 teaspoons Worcestershire sauce, 1 tablespoon reduced-sodium soy sauce, and 1 tablespoon beef bouillon to the slow cooker. To blend, whisk everything together (the bouillon will not be completely dissolved but will dissolve during cooking).

Carefully transfer the beef to the slow cooker using tongs (to avoid burning yourself). Because it will be huge, you will have to cram it in. Not all of it will be submerged in liquid.

Cook on low for 8-10 hours, or until the brisket is extremely tender, turning halfway through. If your brisket is tough, simply cook it longer.

Transfer the brisket to a baking sheet lined with foil. Broil for 5-10 minutes, or until slightly caramelized, brushing with barbecue sauce. Meanwhile, reheat the remaining barbecue sauce in the microwave or on the stovetop.

Brush the brisket with barbecue sauce again, then slice it against the grain or chop it if preferred. Serve straight with the remaining barbecue sauce, or create wonderful sandwiches.