Trim the excess fat from the beef brisket and pat the meat dry with paper towels.
In a small bowl, combine the smoked paprika, garlic powder, onion powder, chipotle powder, sea salt, and black pepper.
Rub the spice mixture thoroughly into all sides of the brisket.
In the bottom of the slow cooker, whisk together the tomato paste, one tablespoon of apple cider vinegar, liquid smoke, and water.
Place the seasoned brisket into the slow cooker, coating the bottom in the liquid.
Cover and cook on low for 7-8 hours until the meat is tender and easily pulls apart with a fork.
Remove the brisket from the slow cooker and let it rest for 10 minutes before chopping it into small, bite-sized pieces.
Toss the chopped meat back into the slow cooker with the remaining juices to keep it moist and savory.
In a separate bowl, toss the shredded cabbage with the remaining half tablespoon of apple cider vinegar and yellow mustard to create a tangy slaw.
Lightly toast the sprouted grain bun, pile the smoky chopped brisket on the bottom half, and top with a generous portion of the crisp slaw.