© Shutterstock The taco is deceptively simple by reputation; tortilla, filling, and perhaps some garnishes or salsa on top. But the reality is that so much goes into the preparation for the myriad fillings of the ubiquitous taco that to dismiss this handheld meal as no more than street food is a huge disservice. Mexican food is a UNESCO-designated cultural treasure, and in the taco category, these vessels of masa, meat or meat-like proteins and spice are widely varied.
But it's also easy to get lost among all the options to stuff in tortillas and fall back on the basics. Which is fine, but if you're not exploring the wide-world of taco fillings, you're doing your palate a disservice. To give you the knowledge you need to live your best taco life, we enlisted the expertise of Steven Alvarez, an assistant English professor at St. John's University in Queens who came to fame when he started teaching a taco literacy course at the University of Kentucky. We discussed the origins and mythology behind some of the most popular tacos around and came to the conclusion that it could very well take years of study to tell the stories of every taco imaginable. In the meantime, here's a handy guide to the taco fillings you're most likely to come across: 
Al Pastor
Tacos al pastor, the more famous cousin to the taco árabe, loosely translates to "shepherd-style" pork. The meat is marinated in a blend of chilies and spices, then slow-cooked on trompo using an open flame. The spinning mound of pork is usually topped with a pineapple, of which thin flecks are often garnished on top of the protein for a sweet, tangy kick.
© Cemitas Puebla Tacos Árabes
One distinct dish that showcases the culinary connection between the Middle East and Mexico is the taco árabes, which utilizes flavorful slices of pork (a departure from halal-friendly proteins of the Arab/Muslim-majority region) from a trompo or spit. The marinated pork is then stuffed into a pillowy, pita-like flour tortilla.
© Jose R. Ralat/Thrillist Barbacoa
Traditionally, Alvarez says barbacoa references the style of cooking meat by the Taino people of the Caribbean. In Mexico, it refers to slow-cooking over an open flame or in a hole dug into the ground until the fatty protein is tender. In northern Mexico and in south Texas' Rio Grande Valley, the economic-yet-flavorful beef head or beef cheeks (cachete) or goat (cabrito) is often utilized and served on weekends, such as at
Vera's Backyard Bar-B-Que in Brownsville.
© Stuart Spivack/Flickr Birria
Head to Guadalajara in the western Mexican state of Jalisco, and you'll find the country's birria capitol. A spicy meat stew, usually prepared with goat that's marinated in a spicy guajillo chili-based broth, birria street vendors are commonplace all over the region. Often served during weddings or other special occasions, birria is traditionally a special occasion dish, but also often comes in taco form. Surrounding states like Michoacán, parts of Durango, and Zacatecas-which specializes in birria de res (beef)-also make variations of the dish.
© Masa Assassin/Flickr Buche
Buche refers to the stomach of the pig. When stewed for several hours with a variety of spices and chiles, the meat breaks down to a tender, somewhat chewy texture. Most would consider buche to be less spongy than beef tripe.
© Photosphere/Shutterstock Cabeza
The meat from the head of a cow is particularly flavorful, typically only requiring salt. Sometimes it's braised to tenderness, while other taquerias may serve it al vapor or steamed. Some spots may only utilize the cheeks, such is the case with barbacoa, while carnicerias may prepare the head whole.
© Al Pastor Authentic Mexican Taqueria Campechanos
Typical in southern Mexico such as in the states of Campeche and Tabasco, campechanos are for when you can't get enough meat in your life. Tacos campechanos are often made with a combination of whatever is leftover to create a new, complex-in-flavor medley of meats. Usually, it's a combination of carne asada or cecina de res (thinly sliced beef), longaniza (a spicy pork sausage), or chorizo and maybe chicarrón, providing a balanced mix of salty, spicy and crunchy.
© Jesus Cervantes/Shutterstock Carne asada
Carne asada literally translates to grilled meat, but in this context it's referring to ranchera or flap steak from the short loin section of a cow. Carne asada is typical in the northern frontier states, in particular Sonora. The meat is usually marinated in a blend of citrus juices, cumin, and other spices and then simply grilled. This particular cut of meat is especially thin, making it easy to just grab a hunk with a tortilla and eat it plain, but in taquerias the protein is typically chopped into small bits.
© Joshua Resnick/Shutterstock Carnitas
The state of Michoacán is carnitas country. Translating literally to little meats, carnitas is made with shredded pork shoulder that's braised or simmered for several hours in its own fat until tender so that the meat easily comes apart. The slow cooking brings out a simple pork flavor, and if done right the shredded meat bits come out slightly crispy on the ends.
© El Dorado Mexican Cuisine Cecina
Cecina, or carne, refers to beef or pork that's been expertly sliced, salted, and dried partially in sheets or strips in the air, sun, or smoke. For beef, a large piece is marinated in a coating of chili pepper, essentially turning it into a continuous roll of slices. The result is smoky meat that easily folds into a tortilla, with no need for chopping up into small bits.
© TheWonderWays/Shutterstock Gallery: 11 Asian Cookbooks We Recommend for Beginners (Taste of Home)
Chapulines
Deriving from the Nahuatl language, chapulines are grasshoppers and are commonly eaten in parts of Mexico. In more recent years chapulines have been touted as one of the most sustainable food sources in the world, though they have been a staple in southern Mexico for centuries. They are often dried and toasted and flavored with lime juice, garlic, and sometimes chili, making for a protein-rich, low-fat, savory, earthy, and crunchy snack, not unlike a bowl of dried shrimp. They can be eaten alone such as at sporting events, but chapulines are also often sprinkled into tacos, tostadas, and even pizza.
© Tacar/Shutterstock Chicharrón
Most of you are probably familiar with chicharones as pork rinds, or fried pork skins. Alone, chicharrones are a satisfying snack while watching the big futbol game. But as a taco filling, they take on a whole new quality. Tacos de chicharrón are soft, not crispy, after being simmered in salsa verde for a spicy, somewhat chewy (but in a good way) combination.
© Playa del Carmen/Shutterstock Chorizo
The Spanish ruled over Mexico for centuries, bringing their language, Catholicism, cattle, and disease. They also brought chorizo, which in Spain is usually cured and smoked. In Mexico, it's sold fresh and uncooked. Mexican chorizo is a blend of minced meat-typically pork (though other meats are also utilized)-that's seasoned with spicy chili peppers. To cook it, the ground meat is removed from its casing. The state of Toluca is considered the capital of chorizo and is available in bright-red or green.
© Playa del Carmen/Shutterstock Cochinita pibil
In the south of Mexico from the Yucatan Peninsula, cochinita pibil reigns supreme. Instead of beef, a suckling pig is marinated with many of the region's citric juices, such as bitter oranges, lemons, limes or vinegar. The pig is usually seasoned with annatto seed, giving it a burnt orange hue, then wrapped in a banana leaf and slow roasted. The result of the slow cooking is an incredibly tender meat.
© Barna Tanko/Shutterstock Cueritos
Cueritos refers to pig skin, but don't confuse them to chicharrones (see above). Instead of deep frying, these thin strips of skin are pickled in vinegar and seasoned with chilis, peppers, oregano, and other spices.
© Playa del Carmen/Shutterstock De canasta/al vapor
No, not a filling, but rather a style of taco that translates to basket for the vessel they sit in after they've been made. Tacos de canasta, also known as tacos al vapor or tacos sudados (sweaty), start with a fried tortilla that's filled with ingredients that have the ability to sit out for several hours at a time. Once assembled, they're steamed and are later sold from a basket by street vendors, particularly in Mexico City (they can also be found in many chilango restaurants stateside). While DF vendors fill them with all kinds of ingredients like tinga or cochinita pibil, the ones filled with potato (which is mashed to a puree consistency) or refried beans tend to hold up the best.
© Juan Salvador/Shutterstock Huitlacoche
Most of the meat fillings can be traced to Spanish colonialism, with the introduction of livestock to the Americas. But there's one ingredient that has been quintessentially tied to Mexico's identity long before the Spaniard invasion and that's corn. And with corn comes huitlacoche. Known by several other names, including Mexican truffle, corn smut, or corn mushroom, huitlacoche is a fungus that grows on organic corn and is extremely rare. But if you do come across huitlacoche on the menu of a Mexican eatery, devour it. When heated or canned (you're not likely to find the fresh variety in most U.S. establishments), the usually white, velvety morsels turn an inky black and the flavor has a rich earthiness to it, similar to that of a mushroom.
Lengua
Spanish for beef tongue, some say lengua is too chewy, but if done correctly, that's not the case. Slow cooked for several hours, then chopped into small, uniform chunks, the texture is smoother and more buttery than other cuts of beef.
© Natalie Holtz/Thrillist Pescado
While fish tacos can be found on menus everywhere, the birthplace of the original is Baja California, which sits along the Pacific Ocean directly south of California. They usually consist of a fried or grilled white fish filet that's topped with cabbage or lettuce, pico de gallo salsa, and some sort of creamy white sauce-either sour cream or a citrusy mayo. Many Baja-area fish taco vendors also make tacos with camarones (shrimp) that are dressed in the same manner.
© Joshua Resnick/Shutterstock Pollo
Pollo means chicken. And if you see this on a menu, the pollo is usually marinated and grilled and then cut into chunks, while other times it's shredded to make tinga (see below). Sometimes, chefs give the chicken a southern-fried twist. And if you've been to Taco Bell relatively recently, you might have seen the pollo act as a deep fried shell.
© Tacos El Panzon Res
Res means beef or livestock. So if you see it as part of any menu item, just know it know it's gonna be cow-related.
© Lyudmila Mikhailovskaya/Shutterstock Sesos
If lengua is smooth, sesos-or cow brains-are custard. The texture is often favored by those who prefer a silky soft meat. Preparation involves boiling down the head until the meat falls off the bone, then gets seasoned or either braised or grilled.
© Suriel Ramzal/Shutterstock Suadero de res
Suadero de res calls for the section of beef between the belly and leg. The meat is stewed in lard for several hours, then fried, resulting in a crispy caramelization. Alvarez says most often, tacos de suadero are associated with Mexico City.
© Marcos Castillo/Shutterstock Tinga
For folks wanting to steer away from shredded pork, beef, goat, lamb or some of the other meaty fillings, there's chicken tinga with origins in the the state of Puebla. Tinga is flavorful chicken thighs are braised in a tomato-chipotle chili sauce and then shredded.
Tripas
Usually referring to the cow's stomach or intestines, tripas require cleaning, boiling, and cooking to avoid a rubbery texture. Traditionally, especially in farming areas, tripas are often prepared in a "disco" made with two tiling discs, which are stacked on top of each other and have a pole welded in the middle. It kind resembles a wok. In the upper disc, the tripas are boiled and cooked and the lower disc holds the charcoal or wood used to heat the ingredients.
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Serena Maria Daniels is writing & reporting at the intersection of halal burgers, Ramadan IHOP, grasshopper pizza, taco literacy & urbanism. She is a recovering daily newspaper reporter and the Chingona-in-Chief at Tostada Magazine.