Buy a large boneless shoulder of pork (2.5kg or so). Mix together 2 tsp each smoked paprika, ground cumin, pepper, and brown sugar, plus 1 tsp salt. Rub over the pork.
Put the pork in a big casserole dish, skin-side up, and pour in 500ml chicken stock. Cover with a lid and cook in the oven at 150C/130C fan/gas 2 for anywhere between 4 and 8 hrs until falling apart. Check every few hours in case it gets dry – if it does, add another mugful of stock/water
Take it out of the oven and put the meat in a big dish, leaving the liquid in the casserole. Cut the skin off, then shred the meat using two forks. Ditch any fatty bits, and skim any excess fat off the surface of the sauce.
Add a mugful of a good smoky BBQ sauce to the casserole, mix it in, then ladle some into a bowl for dipping. Put the pulled pork back in the casserole with the juices so it stays moist. Season to taste.
Fill an oven proof bowl with tortilla chips and cover with the pulled pork, top with the grated cheddar and place under a hot grill until golden and blistered