Heat oven to 150C/130C fan/gas 2. Rub the pork with 2 tbsp of the olive oil. Heat a large non-stick pan until very hot and sear the pork on all sides until golden brown.
Place the meat on a wire rack in a roasting tin. Mix the paprika, mustard powder, garlic and onion salt, and some black pepper with the liquid smoke, if using. Brush all over the meat.
Add 1 cup of water to the roasting tin, cover very tightly with foil and cook for 5 hrs or until almost falling apart.
Drain the juices from the meat into a measuring jug. Shred the pork using 2 forks, discarding the fat.
Skim off the fat from the juices. Mix 125ml of the juices with 4 tbsp BBQ sauce (see recipe in 'goes well with') and pour over the meat. Keep warm until serving, or reheat.
To assemble, pile the meat into the halved brioche buns, spoon over the BBQ sauce, top with coleslaw and pickles, and sandwich together.