In a large bowl, combine masa harina, baking powder, and salt.
Gradually add the chicken or vegetable broth and vegetable oil (or lard) to the masa harina. Mix until you have a smooth dough. If the dough feels too dry, add more broth a little at a time until the desired consistency is achieved.
In a medium bowl, mix the shredded chicken or pork with salsa or tomato sauce, green olives, capers, diced bell peppers, chopped onions, minced garlic, ground cumin, and dried oregano. Season with salt and black pepper to taste.
If using banana leaves, cut them into rectangles large enough to wrap the tamales. If using corn husks, drain and pat them dry.
Spread a spoonful of masa dough onto the center of each leaf or husk. Add a spoonful of filling on top of the masa.
Fold the sides of the leaf or husk over the masa and filling to enclose them. Secure with kitchen twine if needed.
Arrange the wrapped tamales in a large steamer, standing upright if possible.
Steam the tamales over boiling water for about 1-1.5 hours, or until the masa is fully cooked and separates easily from the wrapping. Add more water to the steamer as needed to keep it from drying out.
Allow the tamales to cool slightly before serving. Enjoy with your favorite salsa or hot sauce.
Enjoy your meal!