Put the chipotle paste, oregano, garlic salt, chilli flakes, tomato purée and cider vinegar into a bowl.

Season and stir well and pour the marinade over the pork and rub it over all sides.

Put the pork into the slow cooker, along with all the marinade. Pour in the orange juice and put the lid on the slow cooker.

Set the slow cooker to high and cook for 5 hrs.

Meanwhile put the red onion into a small bowl. Cover with boiling water and leave for 15 mins.

Drain the onions and place them back into the bowl.

Add a good pinch of salt and add the lime juice.

Stir well and leave to pickle for 15 mins. They will turn a bright pink colour.

When the pork is nearly done, preheat the oven to gas 1, 140°C, 120°C fan.

Wrap the tortillas in foil and heat in the oven for 6-8 mins and remove the lid from the slow cooker pull out any bones from the pork.

Spoon out any excess fat from the pot then, using two forks, begin to pull the meat apart until it is all shredded and sitting in all the juices.

When the tacos are warm, remove them from the oven.

Fill each taco with a little lettuce, top with pulled pork and sprinkle with some coriander and the red chilli.