Ingredients:

  Amount  Measure       Ingredient -- Preparation Method
--------  ------------  --------------------------------
                        === for the sauce ===
   4      cups          apple cider vinegar
     1/4  cup           firmly-packed dark brown sugar
   1      tablespoon    red pepper flakes
   1 1/2  teaspoons     ground cayenne pepper
   3      tablespoons   salt -- or to taste
   1      teaspoon      freshly-ground black pepper
                        === for the sop ===
   2      cups          apple cider vinegar
   1      teaspoon      red pepper flakes
   1      teaspoon      salt
                        === for the pork ===
   4      pounds        boneless -- tied pork shoulder
                        -- - (to 5 lbs)
   8                    hamburger buns - -- (to 10 buns)

Preparation:

Preheat an oven to 325 degrees. To make the sauce, in a non-reactive bowl, combine all the sauce ingredients and whisk until well blended. Let stand at room temperature for at least 4 hours. To make the sop, in a small non-reactive bowl, whisk together the vinegar, red pepper flakes, and salt. Place the pork on a rack in a roasting pan. Pour 1 1/2 cups of the sop in the pan. Cook 1 hour per pound, basting every 30 minutes with the remaining sop, until meat is tender, 4 to 5 hours. An instant-read thermometer should register at least 160 degrees when inserted into the center of the roast. Alternatively, to cook in a smoker, heat the smoker to its highest setting using charcoal. Wrap 2 handfuls of hickory smoking chips in heavy-duty aluminum foil and pierce holes all over the top of the foil packet. Bank the ash-covered coals to one side of the smoker. Place the foil packet, holes side up, on the mound of the coals. Fill the water pan and place in the smoker. Cook the pork over medium heat, according to manufacturer's instructions, about 6 hours or until an instant-read thermometer registers 160 degrees. Baste with sop every 30 minutes. Remove the roast from the oven or smoker and let cool about 30 minutes. When cool enough to handle, shred or pull and chop the meat, discarding any fat. Pour 1 cup of the sauce over the meat to moisten it. Make into sandwiches by piling the meat onto the buns, drizzling each with more of the sauce and capping with the bun tops. Store the unused sauce refrigerated in an airtight non-reactive container up to 3 months. Comments: When it comes to barbecue styles, Southerners are almost as tribal as they are about college football loyalties. Eastern Carolinians put vinegar on their pork, western Carolinians use tomato-based sauces and South Carolinians use mustard blends. History stands with the eastern Carolinians -- their tomato-less spiced vinegar is America's oldest barbecue sauce and has been served at pig-pickin's -- whole hog barbecues -- since George Washington was in knee-highs.