Remove the pork belly from the fridge an hour before cooking.
Preheat the oven to 350 F. Tip the marinade into a large dutch oven and spread the pork belly pieces in a single layer in the pan. Pour over your stock. Cook for 2 hours with a lid on.
After 2 hours, remove the lid and cook the pork belly for another hour. This will cook off the remaining liquid and finish rendering the pork fat.
Remove the pork belly from the oven. Transfer the pork pieces to a large flat bottomed skillet. Spoon off as much of the fat as you can from the dutch oven and add it to the skillet with the pork belly pieces. Avoid any solids from the bottom of the pan as these will burn!
Over a medium heat, continue to cook the pork belly in its own rendered fat. The pan should be bubbling but not spitting. Flip the pork belly pieces so that they brown evenly on all sides. This should take about 30 minutes.
When all sides are brown and crispy, remove the pork belly from the pan and drain on some paper towel. Shred the meat with two forks and enjoy! This is especially good paired with Mango Guacamole!