Tamales are a traditional Mexican dish of stuffed masa (corn dough) which is then steamed in a banana leaf. Try finding banana leaves in the frozen section of the grocery store or at specialty Latin markets; if you can’t find the leaves, use foil as a substitute. This recipe comes from Mexico: The Cookbook by Margarita Carrillo Arronte.
Combine the chiles and enough hot water to cover them in a small bowl, and soak for 15 minutes.
Heat 1 tablespoon of the lard in a saucepan over medium heat, add the onion, and sauté for 5 minutes. Put the onion into a food processor or blender, add the avocado leaves if using, garlic, and chiles with the soaking water, and process to a smooth paste. Mix in the black beans gradually, adding some of the cooking liquid if necessary, to return the texture to a smooth paste.
Combine the masa harina, lard, and salt in a large bowl and mix well, adding some chicken stock, if necessary.
Lay out a piece of double cheesecloth (muslin) and arrange a layer of hoja santa. Put the dough on top to form a rectangle, then cover with a layer of the bean paste. From one long end, roll the tamale, using the cheesecloth to help form a cylinder, without trapping the cheesecloth inside.
Remove the cheesecloth and carefully cut slices about 1 inch thick, then arrange each slice inside a banana leaf. Close, fold, and put the tamales vertically into a steamer. Cover the tamales with a damp dish towel and the lid so that the steam doesn’t escape. Steam over high heat until the dough can easily be separated from the husk, 1 hour.
Let stand for 20 minutes before serving.