Roughly chop the marinade ingredients and blend in a food processor.
Rub the pork shoulder in the marinade and allow to rest for up to 6 hours in the fridge (preferably overnight).
Set the oven at 150°C/gas mark 2 and cook the shoulder for 4-5 hours. If it looks like it is getting dry, add some water to the pan, baste the shoulder often during the cooking time. You want the meat to be nearly coming away from the bone when it is cooked.
Place all the ingredients for the jerk rub in a food processor until completely smooth and combined.
Start up the BBQ and rub the jerk rub over the cooked shoulder.
Place the shoulder on the BBQ and cook until you get charred bits of shoulder, which will intensify the flavour (alternatively, cook the pork for an additional 45 minutes in the oven).
The meat should pull away from the shoulder so you can serve it in baps with a nice fresh salsa to go with it.