Tacos Al Carbon

Al pastor (from Spanish, In the style of the shepherd) is a dish developed in Central Mexico, likely as a result of the adoption of the shawarma spit-grilled meat brought by Lebanese immigrants to Mexico.
Being derived from shawarma, it is also similar to the Turkish doner kebab and the Greek gyros. Whereas shawarma is usually lamb-based (thus the "shepherd style" name), gyros and tacos al pastor in Mexico are made from pork.

Pork is marinated in a combination of dried chiles, spices and pineapple. In some places achiote is also added, and then slowly cooked with a gas flame on a vertical rotisserie called a trompo (lit: spinning top), very similar to how shawarma is cooked, with a piece of fresh onion and a pineapple on top.
The juice from the pineapple contains bromelain, an enzyme that breaks down protein and thus makes meat tender. When ready, the meat is then thinly sliced off the spit with a large knife.
It is served on small tortillas, with finely chopped onions, cilantro and a small slice of pineapple, and usually topped with some lime juice and hot salsa.
This meat is a common ingredient in not just tacos, but also gringas, alambres, huaraches, tortas and pizza.

Source: Wikipedia