Add the cumin seeds, black peppercorns and cloves to a pan and heat for a few minutes until lightly toasted and then grind in a spice grinder or pestle and mortar.
Add the dried spices to a food processor along with the onion, chilli peppers, orange juice and lime juice and blend to a paste.
Add the pork cubes to the marinade and leave to marinate for at least 2 hours.
Mix the thinly sliced red onion with the lime juice and set aside for 3 hours, stirring occasionally.
Pre-heat the oven to 150C fan.
Add the pork and marinade to a large cast iron pot with a lid and bring to a boil then put the lid on and transfer to the oven. Cook for 3 hours stiring every 45 minutes, if it starts drying out add a splash of water.
Serve with the pickled onions.