Preheat your pellet or electric grill to 225-250°F (107-120℃). Follow the manufacturer's instructions for your specific grill, and use the wood pellets of your choice. (I used the Competition Blend).
For a standard smoker, use charcoal or wood chips. Preheat it to a similar temperature of around 225°F (107°C).
Place the brisket in the pellet grill, fat-side up, and smoke for 3-4 hours. Insert a meat thermometer into the thickest part of the brisket to ensure accurate temperature.
Smoke the brisket flat until it reaches an internal temperature of between 165-170°F (73-76℃) and your brisket has developed a good bark (flavorful crust that forms on the surface).
Remove from the smoker and tightly wrap it with butcher paper or foil. (Foil cooks faster and makes the brisket tenderer but might ruin the bark. While butcher paper preserves the bark's texture but might take longer to cook.)
Place the wrapped brisket back in the pellet grill and continue smoking until the internal temperature is between 203-205°F (95℃). It usually takes about 3 hours.
Place the wrapped brisket in a cooler or a warm, dry place and let it rest for at least 1 hour, but preferably 2-3 hours. This resting period allows the juices to redistribute throughout the meat and the fibers to relax, resulting in a more tender and juicy brisket. Please don't skip this step.
Slice the brisket against the grain and serve with your favorite barbecue sauce and sides.