One day before - remove the roast from the paper, and sprinkle with 2-3 Tbsp of kosher salt - place in a dish and cover with plastic wrap over night.
Preheat oven to 325°F. Sprinkle cracked black pepper over the already salted roast.
Set an oven-proof Dutch oven over medium-high heat. When it’s warm, add 1 tablespoon neutral oil. When the oil shimmers, place the pork in the pan. Brown it evenly on all sides, about 3-4 minutes per side.
When the meat is brown, remove it and set it aside. Tip out the fat from the pan, if there is excess. Return the pan to the stove, reduce the heat to medium, and add 1 tablespoon neutral oil. Cook the onions and garlic over until they are tender and lightly browned, about 15 minutes. Add the tomatoes and juice, cumin, bay leaves, dried chilies, and paprika into the pot and stir. Nestle pork atop the aromatic base, and add enough beer to come 1½ inches up the sides of the meat. Make sure the peppers and bay leaves are mostly immersed in the juices so that they do not burn.
Increase heat and bring to a boil, then slip the pot, uncovered, into the oven. After 30 minutes, check to make sure the liquid is just barely simmering. About every 30 minutes, turn the pork over and check the level of the liquid, adding more beer as needed. Cook until the meat is tender and falls apart at the touch of a fork, 3½ to 4 hours.
Remove the cooked pork from the oven and carefully remove it from the pan. Using a food mill or whizzing machine, puree the aromatics and strain them through a sieve. Skim the fat from the sauce and then taste, adjusting salt as needed.
At this point, you can either shred the meat and combine it with the sauce to make pork tacos, or slice it and spoon the sauce over the pork to serve it as an entrée. Garnish with chopped cilantro to serve.