Preheat oven to 325 degrees F.
Cut the pork shoulder into 2-inch chunks, trimming and discarding as much of the excess fat as possible. Once the 3 1/2 to 4 pound roast is trimmed you should be left with about 2 1/2 pounds. Sprinkle salt evenly over pieces of pork.
Add 1 tablespoon oil to a 5- to 6-quart Dutch oven and place it over MEDUM-HIGH heat. Cook the meat in batches, adding additional oil as needed, for 6 to 8 minutes or until deep brown on all sides. Transfer the browned pork to a dish and set aside.
Reduce the heat to MEDIUM and 1 tablespoon of oil to the pot. Add the onion and cook, stirring occasionally, for 3 minutes or until lightly browned. Stir in the garlic, cumin, coriander, and oregano and cook for 1 minute. Add the beer, orange juice and chipotle peppers. Bring to a simmer, scraping the bottom of the pot to loosen the browned bits. Return the meat and juices to the pot and return the mixture to a simmer. Cover and transfer the pot to the oven.
Bake for 2 to 2 1/2 hours or until the meat is fork tender and easy to shred.
Use two forks to shred the meat in the pot, mixing it into the liquid. If there's too much liquid, simmer over MEDIUM heat to reduce and thicken it slightly.
Serve in lightly toasted tortillas with optional toppings.