Prepare the Pork Filling:
In a large pot, combine the pork shoulder, chopped onion, garlic, and enough water to cover the meat.
Bring to a boil, then reduce heat and simmer for about 2 hours or until the pork is tender and easily shredded.
Remove the pork from the pot and shred with two forks. Discard any fat.
Return the shredded pork to the pot and mix in the red chile sauce, cumin, paprika, oregano, salt, and pepper. Simmer for 20 minutes, allowing the flavors to meld.
Prepare the Masa:
In a large bowl, combine masa harina, baking powder, and salt.
Gradually mix in the chicken or pork broth and vegetable oil or lard until the masa is smooth and spreadable.
Assemble the Tamales:
Drain and pat dry the soaked corn husks.
Spread a generous amount of masa mixture in the center of each husk, leaving about 1 inch on the sides and bottom.
Add a spoonful of pork filling on top of the masa.
Fold the sides of the husk over the masa and filling, then fold the bottom of the husk up to enclose the tamale.
Repeat until all the masa and filling are used.
Steam the Tamales:
Arrange the tamales upright in a large steamer or a large pot with a steamer rack.
Cover with a wet cloth or additional husks to keep the tamales from drying out.
Steam over medium heat for about 1.5 to 2 hours, or until the masa is fully cooked and pulls away easily from the husks.