Whisk the bourbon, mustard, chili powder, paprika, sugar, granulated garlic, onion powder, cumin, 1 tablespoon salt and 1 teaspoon pepper together in the insert of a 6-quart slow cooker. Use a fork to pierce deeply all over the brisket, then place in the slow cooker and rub all over with the paste. Cover with a lid and cook on low heat until a meat thermometer reads an internal temperature of 185 to 200 degrees F in the thickest part, about 4 hours.
Turn the heat off and remove the insert from the slow cooker. Cool the brisket for at least 15 minutes in the cooking liquid.
Transfer the brisket from the cooking liquid to a large plate or baking sheet, and pat dry with paper towels. Reserve the cooking liquid. In a large cast-iron pan set over medium-high heat, add the oil and heat until it starts to shimmer. Add the brisket, fat-side down, and sear until browned and slightly crispy, 2 to 3 minutes. Use tongs or two metal spatulas to carefully flip the brisket. Cook until browned and slightly crispy on all sides, 1 to 2 minutes.
Transfer to a cutting board and slice the brisket against the grain. Serve hot with the cooking liquid.
To make this dish ahead of time, chill the brisket overnight in its juices after it comes out of the slow cooker. Bring to room temperature for 45 minutes, and then sear and slice the brisket as directed. Reheat the sauce in a saucepan set over medium heat.
Copyright 2015 Television Food Network, G.P. All rights reserved.