- Prepare the brisket: Season with salt and pepper and bring to room temperature. Prepare a smoker for 250-degree heat.
- Smoke brisket until it reaches an internal temperature of about 195 degrees, about 10 to 12 hours.
- When brisket has reached 195 degrees, wrap in plastic wrap and foil and let rest at room temperature for 1 hour.
- Wrap brisket in towels and place in an insulated cooler for 2 to 3 hours before serving. (The meat will continue to cook while it rests. The goal internal temperature after cooling time is between 155 and 165 degrees. If you slice it too early, you’ll end up with dry brisket.)
- While brisket is cooling, make the barbecue sauce: In a bowl, combine mustard, vinegar, and spice blend. Once brisket reaches the goal temperature, carve and serve with mustard barbecue sauce.