With much food that has migrated, often along with the people, from differing parts of the world, it is often quite a task to find authentic manifestations of such cuisine.
The symptoms that infect much of the representations that claim to be of one ethnicity or nationality are several, and one being that dishes are watered down to only include pork, beef, chicken and fish and seafood, excluding such things that derive from animal blood and organ meat. This seems to be the case with Mexican food in NYC, which has a wide distribution with restaurants focusing on Burritos and Fajita (which are not Mexican at all, but Tex-Mex). Guacamole and these two aforementioned items seems to be the main features at places such as San Loco and the more larger representations that dot midtown.
I recently asked a Mexican who lives in Queens as to where there is authentic Mexican food in Manhattan, and I learned of two places, Rosa Mexicano (1st ave below 59th) and Mama Mexico (Upper East). Rosa Mexicano is across from the Chinese owned Japanese restaurant called Eno corner of 58th and 1st ave. (no relation to Brian Eno). I did visit the French Joul Cafe upon finding that Rosa opens only for dinner (Joul Cafe 1070 1st Ave). Joul Cafe has good goat cheese pizza, burgers and of course french food.
To stay on topic here, Rosa Mexicano and Mama Mexico cater mostly to a non-Mexican clientele, but have heard they are quite good. Thus said, I should add that one Mexican server and cook at San Loco told me, they are both Americanized. This honest employee from Mexico told me that "I won't lie to you, I don't eat here [San Loco] to get the food I love from my country".
So, as a rule that perhaps does not need to be stated, find the locations and places where the natives who have not assimilated into American food eating habits eat.
Heading up; over; down or across to El Berrio, or Spanish East Harlem, will offer some great places in the authentic catagory.
1. Kahlua's Café at 2117 3rd Ave below 116 St.
2. Minaya Deli Grocery 2262 2nd Ave on the North East Corner of 116 St.
3. Querido Mexico Lindo 2267 2nd Ave between 116th St & 117th St
4. Taqueria Guadalupe 1743 Lexington Avenue btw 108 and 109 Streets
Kahlua's Café at 2117 3rd Ave just down from East 116 Street on the east side of 3rd Avenue is a very nice local establishment with authentic Mexican food in a small comfortable storefront.
Though not offering organ meats, as much as I could tell on my first visit, Kahlua's Cafe certainly does offer some excellent Mexican food and caters mostly to the Mexican population in the area. You'll enjoy the dishes in an atmosphere that has two large sized photos of the Argentine hero Ernesto "Che" Guevara as well as other celebrated Mexican artists and more. This place is just the way it is, meaning not a contrived atmosphere with tacky fake Mexican themed decor, but one done up very nice by the owner(s). The Mexican patrons talking together with a bucket of Corona and some authentic dishes as well as appreciating the native songs played jukebox (variety of Mexican, as well as Dominican Bachatas) , attests to the authenticity of the place.
Honest photos depicting many of the dishes are on the wall behind the bar. Burritos and Fajitas are included along with Tortas; Cenitas Antojitos Mexicanos (Mexican Delights) such as Chalupas with beef or chicken or cheese, and Sincronizada and Huaraches ("Named after the huaraches sandals the dish is made by flattening rounds of masa dough then topped with various fillings"). Nachos come in a varity with beans and cheese, chorizo and Nachos Tejanos. Bottled beer is 4.00 (Corona; Modelo and Modelo Negro and others). I suspect that their cans of Tecate may be cheaper than the 4.00 bottles.
I have yet to visit Rosa Mexicano or Mama Mexico on the Upper East, and after my experience eating and having a bit to drink at Kahlua's Cafe, I think the need to visit such up market Americanized places becomes much diminished.
A less sitdown place just up and over on 2nd Ave and 116 Street is Minaya Deli Grocery (at 2262 2nd Ave on the North East Corner) serving some really good authentic tacos done up fresh right before of your eyes. (http://www.hatmax.net/EAST_HARLEM/Ave...)
Across 2nd Ave from Minaya Deli and just a door south of a nice Mexican bakery called Mi Querido Mexico Lindo (at 2267 2nd Ave between 116th St & 117th St), is a Dominican owned bar with Presidente for $4.00 and much Dominican Buchata and Tito Puente from the jukebox, making the place a lively alternative to any trendy and contrived hipster bar.
In the quest for neighborhood venues, just over west on Lexington just up from 108 Street is Taqueria Guadalupe (1743 Lexington Avenue). This place does much exhibiting a real neighborhood place, and a visit should be in store for those venturing for authentic Mexican. I have yet to go there but looked inside, and have read great review of the place.
On the organ meat note, it is so sad to see a once cheap and very authentic (Dominican or Puerto Rican) gone that had steal trays of the soupy or stewy offerings that used to be located on the first stretch of Clinton Street up from Dalancey. I think it used to be where Nonna's L.E.S Pizzeria now is.