The corn husks. Cover the husks with very hot water, weight with a plate to keep them submerge and let stand a couple of hours until they are pliable.
Make the filling. In a blender, combine the chiles, garlic, spices and 3 cups water. Cover and blend until smooth. Strain through a medium-mesh strainer into a large (4-quart) saucepan. Add the meat, 3 cups water and 1 teaspoon salt. Simmer, uncovered, over medium heat, stirring regularly until the pork is fork-tender and the liquid has reduced to the consistency of a thick sauce, 1 to 1 ¼ hours. Use a fork to break up the pork into small pieces. Taste and season with salt if necessary. Let cool to room temperature.
Make the batter. In the bowl of an electric mixer, beat the lard (or shortening) with the baking powder and 2 teaspoons salt until light in texture, about 1 minute. Continue beating as you add the masa (fresh or rehydrated) in 3 additions. Reduce the speed to medium low and slowly add 1 cup of broth. Beat in enough additional broth to give the mixture the consistency of soft (not runny) cake batter. It should hold its shape in a spoon. Continue beating for another minute or so, until a ½-teaspoon dollop of the batter floats in a cup of cold water (if it floats, you can be sure the tamales will be tender and light).
Choose the best corn husks. Separate out 24 of the largest and most pliable husks—ones that are at least 6 inches across on the wider end and 6 or 7 inches long. If you can’t find enough food one, overlaps some of the larger ones to give wide, sturdy surfaces to spread the batter on. Pat the chosen husks dry with a towel.
Set up the steamer. You can use a collapsible vegetable steamer set in a large, very deep saucepan (like an asparagus steamer), but you’ll likely have to steam them in batches. To do them all at once, you’ll need something like the kettle-sized tamal steamers used in Mexico (and available at most Mexican grocery stores in the States). You can improvise one by setting a wire rack on four coffee or custard cups in a large kettle. Whatever steamer you’re using, pour a couple of inches of water into the bottom. Line the rack or upper part of the steamer with leftover corn husks to protect the tamales from direct contact with the steam and to add more flavor.
Form the tamales. Cut 24 8-inch pieces of string or tear 24 thin, 8-inch strips from the leftover corn husk. One at a time, lay one of your chosen corn husks on the counter with the wide end toward you. Spread ¼ cups of the batter into a 4-inch square on the husk, leaving a 1 ½-inch border on the end toward you and a ¾-inch border on the other 3 sides. (On very large husks, the border may be much bigger; keep the square to 4 inches.) Spoon about 1 ½ tablespoons filling down the center of the batter from top to bottom. Pick up the two long sides of the corn husk: this will cause the batter curve up and around, encasing the filling. Bring the two long sides of the husk flatly together and roll them around the tamal to create a cigar shape. Finally, fold up the 1 ½ inch tapering section of the husk—the part that’s unfilled. With a string or husk strip stretched left to right on your counter, lay the tamal over the string, about 1/3 of the way up from the bottom. Tie the string to secure the folded up flap. Stand the tamal up in the steamer. Continue until all are filled.
Steam the tamales. If your tamales don’t take up the entire steamer, wad up balls of aluminum foil to fill in the gaps. (This is necessary to keep the tamales standing upright during steaming.) If you have leftover corn husks, distribute them over the tamales and set the lid in place. Bring to a boil over high heat, then reduce the heat to keep the water at a steady—but not raucous—boil for about 1 ¼ hours. Pay attention: If you run out of water, immediately and carefully pour in boiling water to ensure that the steam is as constant as possible. The tamales are ready when you remove one from the steamer and the corn husk peels easily away from the masa. When they’re ready, turn off the heat and let stand about 15 minutes to firm up the tender masa.