Chop the onion in half lengthways, then chop each half into quarters to make wedges. Crush the garlic then set both aside.
In a small bowl, mix together the cumin, oregano, chipotle, and clove to make the spice rub. Set this aside too.
If the pork has skin on it, cut this off and keep to make cracking then pat the meat dry with paper towel. Sprinkle half the spice rub evenly over the top and rub it in so it sticks to the pork. Flip it over and repeat with the other half of the spice rub. Set aside.
Put the instant pot on sauté for 8 mins then pour in the olive oil. Once it's warmed through (about one minute) add in the pork and brown it well on all sides.
If the meat is browned before the timer has finished hit cancel. Add in the chicken stock, orange juice, and salt and pepper. Then add the onion and garlic pushing them down into the liquid. Put the lid on and set to pressure cook for 1 hour and 10 minutes.
Once cooking has finished, hit cancel and let the instant pot release pressure naturally for 20 minutes. While this is happening - switch on your oven grill and line a large baking sheet with baking paper. If the pressure valve hasn't dropped after 20 minutes hit the manual release button to release the rest.
Remove all the pork and place in a large bowl then shred with two forks. The pork should be falling apart as you lift it from the pot.
Take 2/3 cup of the liquid from the pot and pour it over the pork in the bowl. Mix well to completely coat the meat then put it all onto the lined baking sheet. Don't discard the liquid either (see note 2).
Place the baking sheet under the grill for 5 - 10 minutes to get the pork golden and crispy. I only do the one side so the meat stays very moist when serving.
To serve - add the meat to tacos, burritos, or nourishing bowls. Pour a little extra pot juices over the top for lots of added flavour.