1) To make the pulled pork: Rub the pork all over with salt, then coat it with brown sugar, patting it on as best you can.
2) Place the onion in the bottom of a slow cooker. If you don't have a slow cooker, you can cook the pork over a very low burner (preferably with a flame tamer), or in an oven just hot enough to keep it simmering. A slow cooker is the easiest bet here, though.
3) Place the pork shoulder on top of the onion, and drizzle in the vinegar and Worcestershire sauce.
4) If you're using a slow cooker, heat the insert in a microwave for 5 minutes or so, to warm the meat and other ingredients.
5) Set the slow cooker to high, and cook for 3 to 4 hours. Reduce heat to low, and cook for an additional 5 hours or so, until the pork falls off the bone and shreds apart easily when you poke it with a fork.
6) Remove the bone and any whole pieces of fat. Gently stir the pork, until it starts to fall apart. Season to taste with additional salt (up to about 1 1/2 teaspoons, depending on how much you used initially).
7) Drain the pork, saving the juices. Refrigerate pork and juices. When the juices are cold, skim the fat off the top and discard it.
8) To make the rolls: Mix and knead the dough ingredients — by hand, mixer or bread machine set on the dough cycle — to make a smooth dough.
9) Cover the dough and let it rise until it's noticeably puffy, about 60 to 90 minutes.
10) Transfer the dough to a lightly greased work surface, deflate it, and divide it into 12 pieces (about 3 1/4 ounces each). Shape into balls.
11) Dip the top half of each roll into water, then into the seeds. Place the rolls into the cups of a lightly greased hamburger roll pan, or onto a lightly greased or parchment-lined baking sheet. Press gently to flatten.
12) Cover the rolls, and let them rise until puffy, 45 to 60 minutes. Towards the end of the rising time, preheat the oven to 400°F.
13) Bake the rolls until they're a deep golden brown, 22 to 26 minutes. Remove them from the oven, and cool on a rack. If desired, just before serving reheat rolls in a 375°F oven for 5 minutes or so, to crisp.
14) To make the coleslaw: Combine the sugar, celery salt, mustard, mayonnaise, and vinegar in a blender or mini food processor. Toss with the cabbage. Refrigerate until ready to serve.
15) To serve, split each roll. Reheat the pork with some of its juice until hot. Heap each roll with pork, and top with coleslaw. A dill pickle slice is optional.
Yield: 12 rolls; 12 cups pulled pork; and 3 cups coleslaw.