1 (3 – 5 pound) brisket, fat trimmed to about ¼-inch thick
salt, to taste
ground black pepper, to taste
1 packed Tablespoon brown sugar
2 teaspoons smoked paprika
2 teaspoons ground cumin
1 teaspoon mustard powder
1 teaspoon onion powder
1 teaspoon garlic powder
¼ teaspoon cayenne pepper, or to taste (optional)
2 Tablespoons butter (or rendered brisket fat)
1 cup finely chopped onion (about ½ of a large onion)
2 – 3 cloves of garlic, minced
⅓ cup packed dark brown sugar
½ cup ketchup
1 Tablespoon Worcestershire sauce
1 chipotle pepper in adobo sauce, minced (about 1 Tablespoon)
½ cup apple cider vinegar
¼ cup bourbon
reserved brisket juices, skimmed of fat
Preheat the oven to 275°F/135°C and place an oven rack in the middle of your oven.
Season the brisket with salt and black pepper.
Prepare the brisket rub: in a small bowl, mix all of the spice rub ingredients together until they’re well combined.
Gently rub the spice mix all over the brisket, making sure to get the spices into all of the various nooks and crannies.
Make a double-layered aluminum foil pouch for the brisket: place two layers of foil down on the counter, place the brisket (with the fat side up) on the foil, and pull the edges of the foil up around the brisket to wrap it. The pouch needs to be sealed well so that it will keep in all of the moisture. Let the brisket sit (refrigerated) in the spice rub for 3 to 24 hours, or cook immediately.
Place the foil pouch on a baking sheet or baking dish and cook for 3 to 5 hours, depending on the size of your brisket.
Turn off the oven and allow the brisket to rest until it’s cool enough to handle without oven mitts.
Pour the accumulated juices from the brisket into a large measuring cup or a bowl. Skim the fat from the juices, reserving the juices and saving 2 tablespoons of the fat for the sauce. Keep the brisket wrapped in foil and return it to the warm oven while you make the barbecue sauce.
Heat a medium-sized sauce pot over medium heat. Add the onion and cook until it’s softened 4 to 5 minutes. Add the garlic and cook until it’s fragrant about 1 minute. Add the brown sugar, ketchup, Worcestershire sauce, chipotle pepper, apple cider vinegar, and bourbon, and stir to combine. Bring it to a simmer and cook for 2 to 3 minutes, until all of the ingredients are dissolved. Add the reserved brisket juices and simmer until it has reduced to your desired consistency, about 15 minutes. (If desired, blend the finished sauce to make it more smooth.)
Remove the brisket from the oven and open the foil pouch. Turn the oven to broil. Brush the brisket with a good layer of sauce and broil, uncovered, until the top is lightly browned and the fat starts to crisp. Allow the brisket to cool slightly before slicing. Slice the brisket against the grain into ¼-inch slices, and serve with extra barbecue sauce.