How to Make It
In a small bowl, cover the anchos with boiling water; let stand until softened, about 15 minutes. Drain, discarding the soaking liquid.
In a food processor, combine the anchos, onion, garlic, vinegar and salt and puree until smooth. Transfer to a small bowl.
In a large bowl, cover the cornhusks with hot water. Weigh down the husks with a plate and let stand until softened, about 30 minutes. Drain and pat dry with paper towels.
Meanwhile, in the bowl of a stand mixer fitted with the paddle, combine the masa with 1 cup plus 2 tablespoons of water. Beat at low speed until a dough forms, about 2 minutes. Add the lard, beans, cilantro, epazote, scallion and salt and beat, scraping down the side of the bowl, until the mixture is well blended and light in texture, about 5 minutes.
For each tamale, spoon 1/4 cup of the masa in the center of a cornhusk and top with 1 tablespoon of grated cheese and 1 teaspoon of ancho adobo. Roll the husks up and over the filling to make compact cylinders, folding in the sides as you go. Tie the tamales with kitchen string.
Arrange the tamales in a steamer basket and set it over a pot of boiling water. Cover and steam until firm, about 1 hour. Remove the steamer basket and let the tamales stand for 15 minutes. Serve with grated cheese and the remaining adobo.