1 cup plus 2 teaspoons salt
1/2 cup plus 2 tablespoons sugar
3 tablespoons plus 2 teaspoons liquid smoke
1 boneless pork butt (about 4-5 lbs) cut in half horizontally
1/4 cup yellow mustard
2 tablespoons ground black pepper
2 tablespoons smoked paprika
1 teaspoon cayenne pepper
1 1/2 cups ketchup
1/4 cup light molasses
3 tablespoons Worcestershire sauce
1 1/2 tablespoons hot sauce
1/2 teaspoon table salt
1/2 teaspoon black pepper
Dissolve 1 cup salt, 1/2 cup sugar, and 2 tablespoons liquid smoke in 4 quarts of cold water in a large container. Submerge the pork in the brine, cover with plastic wrap, and refrigerate for 2 hours.
While the pork brines, combine the mustard and remaining 2 teaspoons liquid smoke in a small bowl. Set aside. Combine the black pepper, paprika, cayenne, the remaining 2 tablespoons sugar, and the remaining 2 teaspoons salt in a second small bowl. Set aside.
Remove the pork from the brine and dry thoroughly with a paper towel. rub the mustard mixture over the entirety of the pork. Sprinkle the surface of each piece of pork with the spice mixture.
Place the pork in the slow cooker and cook for 10 hours on low. Once the pork is done cooking, transfer from the slow cooker to a roasting pan and pull apart with forks. Carefully pour off any liquid from the bottom of the roasting pan and the bottom of the slow cooker into a heatproof pitcher or large fat separator. Skim off the fat. Place the pork back into the slow cooker.
Place 3/4 cup of the defatted liquid into a medium bowl. Whisk in the sauce ingredients. Stir the sauce into the pork and cook for 2 hours.
Using a slotted spoon, remove the pork from the slow cooker. Serve on a serving platter or on individual buns with any remaining sauce alongside.