1. Preheat the oven to 160°C/gas mark 2½. To make the sauce, gently cook the onion and garlic in the oil for 5 minutes.
2. Mix the paprika, cumin, chilli, pepper in a bowl then add to the pan with the onions and cook for a further 2 minutes.
3. Add the rest of the sauce ingredients and bring to the boil. Reduce to a simmer and cook for 15 minutes.
4. Rub the salt, pepper, cayenne and garlic powder into the opened out beef joint then heat some oil in a pan until hot and seal the meat on all sides.
5. Put the meat in an ovenproof dish, pour over the warm sauce and cover the dish with greaseproof paper and foil.
6. Place in the oven and cook for at least 4/5 hours, turning the meat over in the liquid every 30 minutes or when you remember.
7. With a pair of forks pull the meat apart into chunks and serve with in sub rolls with coleslaw and pickles.