Concept: Mexican cuisine/origin

In the pre-Colombian period, the diet of Mexican ancestors was purely native, with nutrition based on the great product of Mexican agriculture, corn. When thrashed and boiled into a "pozole", the corn could be made into flavorful tortillas and tamales, or rendered into flour for other variations.

Source: 'The best of Mexico- A cookbook'; Evie Righter

 

 

 The diet of corn was supplemented with vegetables and meat. A great variety of spices, known as "chile," could be combined with sweet potato, beans, squash, "chayote", and "jicama". Early mexicans also relied on herbs such as "los quelites", "quintoniles", "huazontles", and a wide range of mushrooms. Indigenous wildlife such as deer, rabbits, armadillos, raccoons, "tepezcuintles", and birds such as turkeys, pigeons, and quails could also be served. Even turtles, snakes, and frogs could be made to complement the native American plate.

After the Conquest and during the colonial period, the country's cuisine changed dramatically with the culinary influences brought along by the Spanish. With the conquistadores and their descendents came a taste for "cebada" , for rice, olives, wines, spices from India, beef, and different kinds of fruit. Today's Mexican cuisine is a blend of the original Indian fare with the Spanish.

Sourced: http://www.mexconnect.com/articles/2817-mexican-cuisine-and-its-origin 

Aztec influence:

 

 The pre-conquest Aztecs were a society that had four main methods of agriculture. The earliest, most basic form of agriculture implemented by the Aztecs is known as “rainfall cultivation.” The Aztecs also implemented terrace agriculture in hilly areas, or areas that could not be used for level ground farming. In the valleys irrigation farming was used. Dams diverted water from natural springs to the fields. This allowed for harvests on a regular basis. The Aztecs built canal systems that were longer and much more elaborate than previous irrigation systems. They managed to divert a large portion of the Cuauhtitlan River to provide irrigation to large areas of fields. The network of canals was a very complex and intricate system.

In the swampy regions along Lake Xochimilco, the Aztecs implemented yet another method of crop cultivation. They built what are called chinampas. Chinampas are areas of raised land, created from alternating layers of mud from the bottom of the lake, and plant matter/other vegetation. These “raised beds” were separated by narrow canals, which allowed farmers to move between them by canoe. The chinampas were extremely fertile pieces of land, and yielded, on average, seven crops annually. In order to plant on them, farmers first created “seedbeds,” or reed rafts, where they planted seeds and allowed them to germinate. Once they had, they were re-planted in the chinampas. This cut the growing time down considerably.

The Aztecs are credited with domestication of the subspecies of wild turkey, Meleagris gallopavo, which is native to this region.^[25]

While most of the farming occurred outside the densely populated areas, within the cities there was another method of (small scale) farming. Each family had their own garden plot where they grew maize, fruits, herbs, medicines and other important plants.

Of the various crops grown by the Aztecs, maize was the most important. Aztec diets centered on it. Maize was grown across the entire empire, in the highland terraces, valley farms and also on the chinampas. Women ground maize into a coarse meal by rubbing it with a grinding stone called a mano against a flat stone called a metate. The Aztecs made tortillas from the corn meal. Other crops that the Aztecs relied upon were avocados, beans, squashes, sweet potatoes, tomatoes, chia, amaranthchilies. These crops were also grown everywhere. Crops that were specific to the lowland regions were cotton, fruits, cacao beans and rubber trees. 

Source: The Aztecs and Maya World'; Charles Phillips

 

Mexican cuisine continues to be based on and flavored by agricultural products contributed by the Mexicas/Aztecs and Mesoamerica, most of which retain some form of their original Nahuatl names. The cuisine has also become a popular part of the cuisine of the United States and other countries around the world, typically altered to suit various national tastes.Source: http://en.wikipedia.org/wiki/Aztec#Aztec_culture

The Aztec marketplace culture has heavily influenced todays Mexican food, key ingredients listed above are still heavily relied upon within Mexican cuisine.