in the middle of a tortilla. Furthermore, dishes analogous to the taco were known to have existed in Pre-Columbian society—for example, the Nahuatl word "tlaxcalli" (a type of corn tortilla). History There is significant debate about the origins of the Taco in Mexico, with some arguing that the taco predates the arrival of the Spanish in Mexico, since there is anthropological evidence that the indigenous people living in the lake region of the Valley of Mexico traditionally ate tacos filled with small fish. Writing at the time of the Spanish conquistadors, Bernal Díaz del Castillo documented the first taco feast enjoyed by Europeans, a meal which Hernán Cortés arranged for his captains in Coyoacán. Others argue that the advent of the taco is much more recent, with one of the more popular theories being that the taco was invented by silver miners in the 18th century, however the first mention of the word "taco" in Mexico was in the 1891 novel Los bandidos de Río Frío by Manuel Payno. Traditional variations There are many traditional varieties of tacos: Tacos al pastor ("shepherd style") or tacos de adobada are made of thin pork steaks seasoned with adobo seasoning, then skewered and overlapped on one another on a vertical rotisserie cooked and flame-broiled as it spins. Tacos de asador ("spit" or "grill" tacos) may be composed of any of the following: carne asada tacos; tacos de tripita ("tripe tacos"), grilled until crisp; and, chorizo asado (traditional Spanish-style sausage). Each type is served on two overlapped small tortillas and sometimes garnished with guacamole, salsa, onions, and cilantro (coriander leaf). Also, prepared on the grill is a sandwiched taco called mulita ("little mule") made with meat served between two tortillas and garnished with Oaxaca style cheese. "Mulita" is used to describe these types of sandwiched tacos in the Northern States of Mexico while they are known as Gringa in the Mexican south and are prepared using wheat flour tortillas. Tacos may also be served with salsa. Tacos de cabeza ("head tacos"), in which there is a flat punctured metal plate from which steam emerges to cook the head of the cow. These include: Cabeza, a serving of the muscles of the head; Sesos ("brains"); Lengua ("tongue"); Cachete ("cheeks"); Trompa ("lips"); and, Ojo ("eye"). Tortillas for these tacos are warmed on the same steaming plate for a different consistency. These tacos are typically served in