How to Make It
In a large skillet, heat the 1 tablespoon of vegetable oil. Add the chorizo and cook over moderate heat, stirring to break up any lumps, until the meat is browned and no trace of pink remains, about 10 minutes. Add the beans and, using a potato masher, mash until creamy. Cook, stirring often, until hot, about 4 minutes. Season with salt and pepper, cover and keep warm.
Heat a griddle or large skillet over moderately high heat. Using your hands, pull out some of the bread from the centers of the rolls to create a small cavity. Brush the cut sides of the rolls with vegetable oil. Transfer the rolls, cut sides down, to the griddle and cook until toasted, about 2 minutes. Turn and cook for about 1 minute longer, until slightly crisp. Transfer to a work surface, cut sides up.
Spread the tops of the bolillo rolls with the goat cheese. Spread the bottoms with 2 cups of the mashed black beans; reserve the remaining beans for another use. Top the beans with the avocado, lettuce and pickled jalapeños. Close the sandwiches, cut in half and serve.
Bolillo and telera rolls, the two classic breads for Mexican tortas, are 6-inch-long oval rolls that are similar to hoagies or soft baguettes; telera rolls are slightly flat. Both types of rolls are available at Latin supermarkets.