Tacos with Pork in Green Sauce (Tacos de cerdo en salsa verde)

In a 3-quart saucepan, cover the tomatillos and chiles with cold water and bring to a boil. Reduce the heat and simmer the vegetables uncovered, turning occasionally, until the tomatillos are tender and khaki-green all over but still intact, about 15 minutes. Reserve the cooking liquid.
Heat the cumin, allspice berries, and clove in a small, dry skillet over medium heat, shaking the pan or stirring the spices until they are fragrant and the cumin is a few shades darker, about 1 minute.
Put the spices in a blender along with 1 cup of the tomatillo cooking water and blend until the spices are ground. Using a slotted spoon, gently lift the tomatillos and chiles out of the remaining cooking water and put them in the blender along with the garlic, cilantro, and 1/2 teaspoon salt. Blend until smooth.
Pat the pork dry and season with the remaining 1 teaspoon salt. Heat the oil in a wide, heavy 4- to 5-quart pot over medium-high heat and brown the pork in batches without crowding, turning occasionally, about 8 minutes per batch.
Return all the meat to the pan and add the tomatillo sauce. Bring to a simmer, stirring to coat the meat, then reduce the heat. Simmer the pork, covered, stirring occasionally, until the meat is tender and the sauce is thickened, 1 1/2 to 2 hours. If necessary, continue to cook uncovered to thicken the sauce. Shred the meat with two forks.
Make tacos with the accompaniments.