Chop up the pork shoulder into 1-2" chunks. Add it to a saucepan and cover with cold water. Add salt and any other aromatics you'd like to use (I used 1/2 onion for this batch). Bring it up to a boil, skim off and discard any foam, then lower heat to simmer, cover, and let cook for an hour or so. Note: I use low on my stove to simmer when covered.
For the Adobo Sauce, start by wiping off any dusty crevasses on the dried chiles, then de-stem and de-seed them. Roast the chiles pieces in the oven (400F) for 1-2 minutes. Alternatively, you can flash roast them on a skillet over medium-high heat for 15-30 seconds per side.
Add the roasted chile pieces to a mixing bowl and cover them with the hottest tap water you've got. Let the chiles reconstitute for a half hour or until you need them. If they float to the surface you can use a small bowl or plate to keep them submerged.
The pork will be ready after cooking for an hour -- when it's close I start to build the Adobo Sauce. Drain the chiles and add them to a blender along with the remaining Adobo Sauce ingredients: 2 chipotles in adobo (optional), 4 peeled garlic cloves, 2 teaspoons Mexican oregano, 1/4 teaspoon cumin (optional), 1/2 teaspoon salt, freshly cracked black pepper, 2 tablespoons white vinegar, 2 tablespoons stock or water (or the pork boiling liquid). Combine well. You may need to add additional splashes of liquid to get it to combine -- I added another few tablespoons of the pork boiling liquid until it combined into a thick, paste-like substance.
Preheat a glug of oil (or lard) in a skillet over medium heat. Add the adobo sauce and cook for a few minutes, stirring regularly. Add 1/2 cup liquid and combine well -- you can use stock, water, or the pork boiling liquid.
Shred the cooked pork using two forks and add it to the adobo mixture. Combine well and bring it up to temp. Feel free to add splashes of liquid if you think it needs it to combine. Salt to taste.
Serve pork mixture immediately. Store leftovers in the fridge where it will keep for a few days.