Make the meat filling: Combine the chili powder, kosher salt, paprika, smoked paprika, garlic powder, onion powder, cayenne pepper, black pepper and cumin in a small bowl. Divide the mixture in half and reserve one half for later use.
Cut the pork butt into 6 equal pieces and place in a 6- to 8-quart saucepan. Add half of the spice mixture and enough water, 3 to 3 1/2 quarts, to completely cover the meat. Set over high heat, cover, and bring to a boil. Once boiling, reduce the heat to low and simmer until the meat is very tender and falling apart, 2 to 2 1/2 hours. Remove the meat from the cooking liquid and set aside, then remove the cooking liquid from the pot and reserve.
Let the meat and liquid cool slightly. Remove any large pieces of fat and shred the meat into small pieces, pulling it apart with your hands or two forks.
Place a 4-quart saucepan over medium heat and add the vegetable oil. Once shimmering, add the onion and cook, stirring occasionally, until semi-translucent, about 3 minutes. Add the garlic, jalapeño, and remaining spice mixture and cook for another minute. Add the meat and cook until it is heated through, 2 to 3 minutes. Remove from the heat.
Prepare the wrappers: While the meat is cooking, put the husks in a large bowl or container and submerge completely in hot water. Soak the husks until they are soft and pliable, at least 45 minutes or up to 2 hours.
Make the dough: Combine the cornmeal, salt, and baking powder in a large mixing bowl. Add the lard and, using your hands, knead together until the lard is well incorporated into the dry mixture. Gradually add enough of the reserved cooking liquid to create a dough that is the consistency of thick mashed potatoes. The dough should be moist but not wet. Cover the bowl with a damp towel and set aside until ready to use.
Assemble the tamales: Remove a corn husk from the water and pat dry to remove excess water. Working in batches of 6, lay the husks on a towel and spread about 2 tablespoons of the dough in an even layer across the wide end of the husk to within 1/2 inch of the edges. Spoon about 2 teaspoons of the meat mixture in a line down the center of the dough. Roll the husk so the dough surrounds the meat, then fold the bottom under to finish creating the tamale. Repeat until all husks, dough, and filling are used. Tie the tamales around the center, individually or in groups of 3, with kitchen twine.
Cook the tamales: Stand the tamales upright on their folded ends, tightly packed together, in the same saucepan used to cook the meat. Add the reserved meat cooking liquid and additional water so the liquid comes to 1 inch below the tops of the tamales. Try not to pour the broth directly into the tops of the tamales. Cover, place over high heat and bring to a boil, about 12 minutes. Remove the lid, reduce the heat to low to maintain a low simmer, and cook until the dough is firm and pulls away easily from the husk, 1 to 1 1/2 hours.
Serve the tamales warm. For a "wet" tamale, serve with additional simmering liquid. Store leftover tamales, tightly wrapped in plastic wrap, in the freezer for up to a month. To reheat, remove the plastic wrap and steam until heated through.