Step 1: Prepare Corn Husks: Place dried corn husks in a large bowl and cover with hot water. Soak for at least 30 minutes or until pliable. Weigh down with a plate to keep them submerged. Drain when ready to use.
Step 2: Make Chile Colorado Sauce: In a dry skillet over medium heat, lightly toast the ancho and guajillo chiles for 30 seconds per side until fragrant. Be careful not to burn them. Transfer to a bowl, cover with 4 cups hot water, and let soak for 20-30 minutes until soft.
Step 3: Blend Chile Sauce: Drain the chiles (reserve the soaking liquid). In a blender, combine the rehydrated chiles, 1/2 chopped onion, 4 cloves garlic, cumin, oregano, 1 teaspoon salt, and 1/2 cup reserved chile liquid or chicken broth. Blend until very smooth. Strain the sauce through a fine-mesh sieve into a saucepan, pressing down on the solids to extract all liquid. Discard solids. Simmer the sauce over medium-low heat for 15-20 minutes, stirring occasionally, until it thickens slightly and flavors meld. Set aside.
Step 4: Cook Pork Filling: Place pork shoulder chunks in a large pot or Dutch oven. Add quartered onion, smashed garlic, 1 tablespoon salt, peppercorns, and enough chicken broth or water to cover the pork. Bring to a boil, then reduce heat, cover, and simmer for 1.5-2 hours, or until pork is fork-tender. Remove pork, reserving cooking liquid. Shred the pork using two forks. In a bowl, combine shredded pork with 2 cups of the prepared Chile Colorado sauce. Mix well.
Step 5: Prepare Masa Dough: In a large bowl or stand mixer, beat the lard or shortening on high speed for 5-7 minutes until very light and fluffy. In a separate bowl, whisk together masa harina, baking powder, and 2 teaspoons salt. Gradually add the masa harina mixture to the beaten lard, alternating with warm chicken broth (or water), beating until a soft, fluffy dough forms. If desired, mix in 1/2 cup of the Chile Colorado sauce for flavored masa. Test the masa: drop a small piece into a glass of cold water; it should float. If not, beat for a few more minutes and retest. The masa should be light and spreadable.
Step 6: Assemble Tamales: Take a rehydrated corn husk (wide end up). Spread about 2-3 tablespoons of masa evenly over the wider part of the husk, leaving a border of about 1 inch on the top and sides. Place 1-2 tablespoons of pork filling in the center of the masa. Fold one side of the husk over the filling, then the other, overlapping slightly. Fold up the narrow bottom end of the husk to seal. If desired, you can tie the tamales with thin strips of corn husk, though this is optional. Repeat with remaining husks, masa, and filling.
Step 7: Steam Tamales: Arrange tamales upright in a large steamer pot over boiling water. Do not let the tamales touch the water. You can line the bottom of the steamer basket with extra corn husks to protect the bottom layer of tamales. Cover the steamer with a lid. Steam for 1.5 to 2 hours, or until the masa easily separates from the husk. Check water level periodically and add more hot water if needed. Allow tamales to rest for 10-15 minutes after steaming before serving.
Step 8: Serve: Serve warm with your favorite toppings like salsa, sour cream, or cotija cheese. Enjoy the fruits of your labor!