Rinse and dry the pork forequarter. Remove any excess fat and sinew but leave the rind attached.
Combine the garlic, brown sugar, dried oregano, cumin, paprika, cayenne pepper, ground chilli, salt and orange zest in a small bowl and mix to form a paste. Rub the paste all over the pork (rindless side).
Place the onions in the base of the slow cooker, put the pork on top with the rind facing down and pour the orange juice and pulp all over the top of the pork.
Cook on low for 8 hours. Once or twice during cooking, spoon the orange juice over the top of the pork.
Remove pork from slow cooker and allow to cool slightly. Remove the rind and discard. Using two forks, shred the pork. It will be so tender that it literally falls apart. Spoon a little of the leftover juices from the slow cooker over the shredded pork to moisten the meat as pork can dry out.
Recipe by Mrs Organised at http://www.mrsorganised.com.au/2015/04/17/mexican-slow-cooker-pulled-pork/