Preheat oven to 160°C. Combine sugar, paprika, salt, mustard powder, celery salt and pepper in a bowl. Place pork on a large chopping board. Remove and discard netting. Using a sharp knife to remove skin and set aside. Place pork in a roasting pan. Sprinkle with sugar mixture, rub it into the pork. Add beer to base of pan and cover tightly with foil. Cook in oven for 3-3.5 hours or until pork is very tender.
Meanwhile, combine ingredients for sauce in a small saucepan over medium heat. Stir until sugar has dissolved and mixture comes to the boil. Simmer for 15 minutes or until sauce thickens slightly and is reduced by a third. Cool.
Using 2 forks, shred pork evenly and place on a platter. Serve with the sauce and coleslaw.
Cut pork rind into 1cm-wide strips, toss with 1 tbs of olive oil and season with sea salt flakes. Place on a deep baking tray lined with baking paper. Cook on top oven shelf, draining fat regularly.