In a large pot, cook the pork shoulder over medium heat until browned on all sides.
Add the chopped onion and garlic and cook until softened.
Stir in the chopped tomatoes, bell pepper, ground cumin, paprika, and dried oregano. Cook until the vegetables are tender and the pork is cooked through, about 20 minutes.
Season with salt and pepper to taste.
If using, stir in the chopped olives, capers, and raisins. Let the filling cool slightly.
In a large bowl, combine the masa harina, baking powder, and salt.
Gradually add the chicken or vegetable broth and vegetable oil (or melted butter), mixing until the dough is soft and pliable. You may need to adjust the amount of broth to get the right consistency.
Drain the corn husks and pat them dry. Lay one husk flat on a clean surface.
Spread a thin layer of masa dough (about 1/4 inch thick) over the lower half of the husk, leaving a border along the edges.
Place a spoonful of the pork filling in the center of the masa.
Fold the sides of the husk over the masa and filling, then fold up the bottom of the husk to enclose the tamale. Tie with a strip of husk or kitchen twine if needed.
Repeat with the remaining husks, masa, and filling.
Place a steamer basket over boiling water. Arrange the tamales upright in the basket, leaning them against each other to keep their shape.
Cover the tamales with a wet cloth and steam for about 1.5-2 hours, or until the masa is cooked through and separates easily from the husk.
Let the tamales cool slightly before serving. Enjoy them with your favorite salsa or hot sauce.
Enjoy your meal!