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.