Preheat your smoker to 225°F using clean-burning oak or hickory wood for authentic Texas flavor.
Trim the beef brisket of excess hard fat, leaving about a quarter-inch of the fat cap to keep the meat moist during the long cook.
In a small bowl, combine the sea salt, black pepper, garlic powder, and onion powder to create a dry rub.
Apply the rub generously to all sides of the brisket, pressing it firmly into the meat to ensure it adheres.
Place the brisket in the smoker and cook until the internal temperature reaches 165°F and a dark, mahogany bark has formed.
Wrap the brisket tightly in peach butcher paper and return it to the smoker until the internal temperature reaches 203°F.
Remove the brisket and allow it to rest in an insulated cooler for at least 1 hour to let the juices redistribute.
While the meat rests, toss the shredded cabbage and sliced red onion with apple cider vinegar and a pinch of salt for a bright, tangy side.
Slice the brisket against the grain into thin strips and serve alongside the vinegar slaw.