Preheat the oven to 180C/160 fan/Gas 4, season pork with 1 TSP of salt and pepper. Add to a large, straight-sided skillet along with onion and 355ml of water. Cover with foil and transfer to the oven. Cook for 2 hours.
Meanwhile, in a medium saucepan, combine 1 teaspoon salt, the juice of three Jaffa Oranges, ketchup, brown sugar, vinegar, Worcestershire sauce, and hot sauce. Bring to a simmer and cook until mixture has thickened, 18 to 20 minutes.
Remove skillet from oven and coat pork with sauce. Return to oven and cook, uncovered, until tender, about 2 hours, basting pork with sauce every 15 minutes. Skim fat, and shred pork and toss with reserved sauce to serve.
