Season the pork with salt and place it inside the pressure cooker.
To make the Achiote sauce, place the orange juice, lime juice, vinegar, Achiote paste, peppercorn kernels, garlic cloves, onion, and oregano in your blender jar. Process until you have a smooth sauce.
Pour this Achiote mixture over the pork, add the 2 bay leaves, then close & lock the lid of your pressure cooker. Cook the meat using the manual option for 45 minutes in the pressure cooker setting.
After the 45 minutes, and once the release valve allows it, remove the lid. Shred the meat, then check to see if it needs more salt. After this, cook for 10 additional minutes in the manual setting with the lid off. This will allow the shredded meat to continue absorbing the Achiote flavor, and also let the sauce thicken a little bit.
To make the sandwiches, start by cutting open the rolls you’re going to use. Spread mayonnaise on one half, and refried black beans on the other. Next, spoon on some of the shredded pork, then top it with some shredded lettuce, one or two tomato slices, and a couple of white onion slices. This pork in achiote sandwich is usually served with pickled jalapeño peppers or pickled habanero peppers, depending on the region. Enjoy!