What is "authentic" Mexican food, and is it allowed to change over time? If, for instance, authentic Mexicans and Mexican-Americans have been eating machine-made tortillas for 4 generations... is a handmade tortilla authentic, or a shibboleth?

What is authentic can change over time as culture changes. 

Good eats are good eats!

You've touched on something that irritates me a lot. Urban white people in particular like to think that they know exactly what "authentic" Mexican food is, and seem to enjoy the one-upmanship of demonstrating their enviable knowledgeability of it every chance they get.

It's even more annoying when they consider Mexican-American people to not be "authentic" enough because they don't cook some more obscure dish that said white person has the good fortune to be intimately familiar with thanks to a summer visit to central Mexico when they were in college.

The question of what is or is not authentic can be interesting, but as with all things it's important to be respectful about it. We also have to be OK with Mexican culture evolving over time, just like every culture does, and to keep in mind that it's not their job to put on a performance for us and stay in their little box of authenticity.

Just about every white American family cooks spaghetti, even if they are like my family and have no Italian heritage to speak of. Is it then "authentic" white people food? To some extent we don't care, because we tend to think of our culture as the default and it doesn't matter whether we're authentic or not, and we are allowed to embrace change by borrowing liberally from other cultures.

We certainly need to allow other cultures to do the same, and should never shame Mexicans or anyone else for not being "authentic" enough by our ideas of what their culture should be.

I know this post is about Mexican food in the United States of America but recent trips to Mexico City caused me to totally reconsider "Mexican Food".  I think it's time we got some of this cuisine in the USA.

Ensalada Papalotl $66 MEX at La Casa Del Pan, Mexico DF — at La Casa Del Pan.

Short Rib con mole negro MÉX $298 (amazing) Corazón de Maguey — at Corazón de Maguey.

Sopa maiz con regaliz (liquorice) MEX$90.00 at Zapote, Colonia Roma, México DF — at Zapote.

Venison Timbale - Tzic de Vanado (venison) MEX $185 at Riviera, Colonia Roma, México DF — at Riviera Del Sur Roma.

Arroz Negro con Salmon ($220 MEX) at Cantina Riviera Colonia Roma — at Cantina Riviera.

Salsas made table side to order at Cantina La Antigua, Mexico DF — at Cantina La Antigua de Colón.

Garlic Octopus - Pulpos a al mojo de ajo (MEX $200) at Cantina la Antigua de Colon — at Cantina La Antigua de Colón.

Chicken pozole (MEX $75) at Sanborns, Montes Urales — at Sanborn's Plaza Lomas.

Shrimp and Marlin Brochettes: Tortios de Camarón y Marlin y Chile Güero (MEX $71) at Mi Gusto Es, Pedregal, México DF — at Mi Gusto Es !!

Simple steak taco: Taco en el Taqueria el Califa, Insurgentes, Mexico City — at Taqueria el Califa.

Guacamole encounter of the first kind at Maria Bonita Pedregal Cantina — at Cantina María Bonita.

Quesos Rellenos de Pastor (MEX $101) - yes that's a taco shell made of cheese! - at El Huequito, Plaza DeToros, México CDMX — at El huequito (plaza de toros).

You can DYI those dishes, right,  because expensive!

I LOVE Rick Bayless on PBS' "Mexico, One Plate At A Time." Authentic  and nouvelle and yum.  http://www.rickbayless.com/tv-books/mexico-one-plate-at-a-time-season-8/

The challenge with one plate at a time is deciding which plate!