Prepare the corn husks by soaking them in warm water for at least 30 minutes to make them pliable for wrapping.
In a mixing bowl, combine masa harina, baking powder, salt, and ground cumin. Mix well.
In a separate bowl, beat the lard or shortening until creamy. Gradually add the masa harina mixture, alternating with chicken broth, and mix until the dough is light and fluffy. You may need to add more broth if the mixture is too dry.
In another bowl, mix the shredded pork with green salsa until well combined.
To assemble the tamales, remove a soaked corn husk and spread about 1/4 cup of the masa dough on the wide end of the husk, leaving about 1 inch of space at the bottom and sides. Place a tablespoon of the pork filling in the center of the masa.
Fold the sides of the husk over the masa and filling, then fold the bottom up to secure. Repeat with remaining husks, masa, and filling.
Place a steamer insert in a large pot and add water, making sure the water does not touch the tamales. Stand the tamales upright in the steamer and cover with a wet cloth or more corn husks.
Cover the pot and steam the tamales for about 90 minutes, adding more water as needed. They are done when the masa separates easily from the corn husk.
Let the tamales cool for a few minutes before serving.