Lightly trim the pork butt if it hasn’t been done already, then cut it into 2- to 3-inch cubes. In a large pot, place the pork, shallots and garlic, cover with water and bring to a boil. Once boiling, reduce the heat to a simmer and skim the surface as needed. Cook for 2 hours, or until tender.
In the meantime, puree the peppers with about 1½ cups of their soaking water. Take the pork out of the liquid and reserve the broth for making the masa. Shred the meat in a bowl and add the cooked shallots, garlic and the chili puree to it. Toss this mixture together and season with the toasted cumin and salt.
In a stand mixer fitted with a paddle attachment, add the lard and cream it until it’s light and fluffy.
In a separate bowl, mix the masa harina with the baking powder and salt, then gradually add the dry ingredients to the lard a little at a time. Add the stock—you want the masa to be pretty smooth and not too stiff so it can spread easily.
Pat the corn husks dry and, using your hands, add 3 tablespoons of masa—about the size of a golf ball—to the center of the smooth, concave side of one of the corn husks with the tapered side facing away from you. Spread it out in the center of the husk leaving room at the top and bottom for folding. Place 2 tablespoons of the pork filling in the center of the masa then fold the sides of the masa around it so that the pork is completely covered. Fold the tapered end of the husk over, toward the bottom. Repeat with the remaining husks to make 24 tamales.
Steam the tamales with the bottom of the husk facing down for about 45 minutes, or until the masa releases from the husk. Let rest for 10 to 15 minutes and enjoy!