Make the salt water brine by combining kosher salt and water in a large bowl. Stir well to mix, until salt is dissolved.
Pat the pork dry. Cut the pork into 3 inch cubes, then place into the salt water brine.* Cover with plastic wrap, and refrigerate for 1 1/2 hours.
Remove the stem and seeds from the ancho chile, and place it in a bowl. Cover it with boiling water, and set a small plate on top of the chile to keep it submerged. Let it rehydrate for 30 minutes. Once it is rehydrated, roughly chop it and set aside.
Combine the brown sugar, Mexican oregano, smoked paprika, cumin, and salt in a small bowl. Whisk to combine, and set aside.
Once the pork is done brining, remove it from the brine and pat it dry.
Heat a wide, deep pot (preferably a dutch oven) over medium-high heat. Add the vegetable oil, and once the oil is hot, carefully brown the pork on all sides. If necessary, work in batches so the pork isn't overcrowded.
Preheat the oven to 300 F.
Sprinkle the seasoning blend all over the browned pork. Use tongs to toss the pork around until it is coated in the seasoning.
Pour pineapple juice into the dutch oven, stirring it to loosen up any browned bits on the bottom. Stir in onions, chopped ancho chile, and smashed garlic, and cook for 5 minutes until onions are very soft and starting to brown.
Stir in bourbon, beer, milk, and bay leaf. Squeeze in orange pieces, then tuck the orange pieces in with the pork. Pour in enough water to cover the pork (about 2-3 cups).
Cover the top of the pot with foil, then place the lid on. Cook for 3 hours at 300 F, checking a couple of times during the cooking process to be sure the pork stays covered with liquid. Add a cup of water if necessary during the cooking process.
Once the pork is fall-apart tender, shred it directly into the liquids in the dutch oven. Transfer most of the shredded pork to small a rimmed baking sheet, and pour about a cup of the liquid on top of it.
Broil pork and liquids until crispy, about 3-4 minutes. Serve on warmed tortillas with chopped onion, cilantro, or your favorite toppings!