1. In a food processor, combine pork, water, sugar and salt. Puree this on high speed for 30 - 60 seconds or until completely smooth.
2. Divide the pureed pork into 4 equal portions weighing 4 ounces each.
3. Line a baking pan with parchment paper. With moist fingers form a patty from each portion of pork on the lined baking sheet in a rectangle shape measuring 6 1/2 inches by 3 inches.
4. Place another sheet of parchment paper over the formed pork patties and freeze it for 2 hours or until the meat has frozen.
5. Preheat a large skillet over medium heat.
6. Remove the baking sheet from the freezer and keep aside. Slice the sandwich roll in half and keep aside.
7. In the hot skillet, place the bread slices and heat until both sides turn light brown and remove.
8. Place the pork pieces on the hot pan and cook each side for 3-4 minutes or until browned in spots. Remove on a plate and let it cool.
9. In a bowl, pour the barbecue sauce, dip each of the pork patties into this sauce completely with the help of tongs. Then place one over a slice of the sandwich roll, arrange 2 dill pickles, chopped onion on the pork and top it with the other sandwich slice.
10. Serve right away with ketchup and mayonnaise.