Allow brisket to reach room temperature.
Preheat your Z Grills pellet smoker to 300 °F.
Mix salt and pepper. Apply brisket rub liberally and evenly on all sides of the brisket to evenly distribute the flavor.
Place brisket fat side down on the grates. Close the lid and cook for 2 hours.
Remove brisket from the smoker and place in a double layer of foil.
Spritz the brisket with a little bit of apple cider vinegar and tightly wrap it with the foil.
Place it back on the smoker, and cook for about 3 more hours, or until internal temperature of the brisket reaches 203 °F.
Once the brisket reaches 203 °F, remove it from the smoker. Open the foil slightly to allow it to vent for about 5 minutes.
Seal the foil and allow the brisket to rest for 45 minutes.
Unpack the brisket. Slice against the grain and serve.