Bring a kettle of water to a boil. Rinse the corn husks well, then put them in a large bowl and add boiling water to cover them. Soak the husks for at least 2 hours.

Put the olive oil in a medium saucepan over medium heat. When it’s hot, add the onion and cook, stirring occasionally, until soft and golden brown, 8 to 10 minutes. Add the cumin and cayenne and season with salt and pepper; cook, stirring, until fragrant, about 1 minute. Add the black beans and ¼ cup water; cook until the beans are hot, 2 to 3 minutes, then purée partially with an immersion blender. Set aside.

Put the stock in a medium pot over medium-low heat. While the stock is heating, beat the butter with the paddle attachment of a stand mixer (or with a handheld mixer in a large bowl) until light and fluffy. Combine the masa, the baking powder, and 1 teaspoon salt in a separate large bowl. With the mixer running, add about 1 cup of the masa mixture to the butter, followed by about 1 cup of the stock. Repeat until all the masa and stock have been incorporated.

Lay a corn husk on a clean work surface with the edges curling up. Spread about 3 tablespoons of the masa mixture into a rectangle along one of the long edges of the corn husk, leaving at least 2 inches of empty corn husk on each side of the masa. Spread about 1½ teaspoons of the black bean mixture and about ½ teaspoon of the goat cheese on the masa near the edge of the corn husk. Roll up the corn husk to enclose the masa and fillings, folding in the edges of the corn husk as you roll. Tear one of the remaining corn husks into strips and tie one of the strips around the tamale to prevent it from unfurling. Repeat with the remaining corn husks, masa, black beans, and goat cheese.

Put 1 inch of water in a large pot. Put the tamales in a steamer over the water, cover the pot, and bring the water to a boil over high heat. Reduce the heat to medium-high and steam until the tamales are firm, about 50 minutes, adding more water if all the water evaporates. Serve hot or warm. (Store leftover tamales wrapped in foil in the refrigerator for up to several days.)