Cook the pork.

Place the pork shoulder in a large pot with the onion, garlic, bay leaves, and salt. Add enough water to cover.

Bring to a boil, skim any foam from the surface, then reduce to a gentle simmer.

Cover partially and cook for approximately 2 to 2 1/2 hours, or until the pork is fork-tender.

Remove the pork, let it cool enough to handle, and shred it into bite-size pieces.

Strain and reserve the cooking broth.

Soak the corn husks.

Place the dried corn husks in a large bowl or clean sink filled with hot water.

Use a plate to keep them submerged.

Soak for 30 to 60 minutes until flexible, then drain and pat dry.

Prepare the dried chiles.

Remove the stems and seeds from the guajillo and ancho chiles.

Briefly toast them in a dry skillet over medium-low heat for approximately 10 to 15 seconds per side, just until fragrant.

Transfer to a bowl, cover with hot water, and soak for 15 to 20 minutes until softened.

Blend the chile sauce.

Drain the softened chiles and transfer them to a blender.

Add the garlic, onion, Mexican oregano, optional cumin, and 1 1/2 cups of reserved pork broth.

Blend until smooth.

For a silkier sauce, strain through a fine-mesh sieve.

Season the pork filling.

Heat one tablespoon of oil in a saucepan over medium heat.

Carefully add the blended chile sauce and simmer for 8 to 10 minutes, stirring occasionally.

Season to taste.

Add the shredded pork and stir until evenly coated.

The filling should be moist but not watery.

Remove from the heat and set aside.

Beat the fat.

In a large mixing bowl, beat the softened lard or vegetable shortening for 3 to 5 minutes until creamy and lighter in texture.

Prepare the masa.

In a separate bowl, combine the masa harina, baking powder, and salt.

Gradually add the dry ingredients to the beaten fat, alternating with warm pork broth.

Mix until smooth and soft.

Start with 3 cups of broth, then add more gradually if necessary.

The masa should be easy to spread, similar to thick hummus.

Spread the masa.

Place one softened corn husk on your work surface with the wide end facing you.

Spread approximately 3 tablespoons of masa over the upper, wider portion, leaving room along the sides and at the narrow end for folding.

Add the filling.

Place approximately 2 tablespoons of red chile pork filling down the center of the masa.

Avoid overfilling.

Fold the tamales.

Bring one side of the husk toward the center, allowing the masa to fold over the filling.

Fold the opposite side over it, then fold the narrow bottom end upward.

Leave the upper end open or secure with a strip of soaked husk if preferred.

Repeat with the remaining ingredients.

Prepare the steamer.

Add water to a large steamer pot fitted with a rack, keeping the water below the rack.

Line the rack with spare corn husks.

Arrange the tamales upright with the open ends facing up.

Cover with additional husks and place the lid on the pot.

Steam the tamales.

Bring the water to a steady simmer.

Steam for approximately 60 to 90 minutes, checking the water level periodically and carefully adding hot water as needed.

Begin testing around the 60-minute mark.

Remove one tamal and let it rest for several minutes before opening.

The masa should be cooked through, cohesive, and release reasonably cleanly from the husk.

If it's still wet and pasty, continue steaming.

Rest and serve.

Turn off the heat and allow the tamales to rest for 10 to 15 minutes.

Serve warm with salsa, beans, or your favorite Mexican sides.