How to Make It
In a large nonreactive saucepan, bring the vinegar to a boil over moderate heat. Add the sugar, dry mustard and salt and simmer until the dry ingredients are completely dissolved, whisking well. Add the pineapple juice, Worcestershire sauce, onion, oil and 1/4 cup of the barbecue sauce and whisk to mix. Remove the pan from the heat and let the marinade cool to room temperature, then refrigerate until cold.
Remove the thin, papery membrane from the back of each rib. Insert a sharp implement, such as the tip of a meat thermometer, under the membrane (the best place to start is at the end of the bone). Using a dishcloth or pliers to gain a secure grip, pull off the membrane. Whisk the marinade once more, then add the beef ribs. The ribs should be completely covered by marinade. Cover the pan and refrigerate the ribs overnight, stirring once or twice.
Set up your smoker and preheat it to 250°. Drain the ribs, discarding the marinade. Arrange the ribs in the smoker, bone side down, and toss 1 cup of wood chips on the coals. Cook the ribs until darkly browned and very tender, 3 to 6 hours (depending on the rib size). Replenish the charcoal and wood chips every hour. (There is no need to add wood chips after 4 hours.) When the ribs are cooked, the meat will have shrunk back from the ends of the bones by about 1/2 inch. Transfer the ribs to a platter, baste with the remaining barbecue sauce and serve.