Heat the oven to 300°F and rub the pork shoulder with the salt and black pepper.
Place the pork in a covered Dutch oven with 1/2 cup vinegar and roast for 3 1/2 to 4 hours until it reaches about 195°F and shreds easily.
Whisk the remaining vinegar with 1 tablespoon brown sugar and the crushed red pepper.
Rest the pork for 15 minutes, shred it and toss it with half the vinegar mixture; return it to the pot until it is steaming and at least 165°F.
Stir the cabbage with the mayonnaise, mustard, remaining brown sugar and 3 tablespoons of the remaining vinegar mixture.
Pile hot pulled pork onto each bun and top it with 1/2 cup slaw.
Close the sandwiches and serve before the cabbage loses its crunch.