I learned all this when I actually went to Mexico and they were putting carrots and cabbage and shit in my tacos, and the only places that had burritos were there to exploit the dumb gringos looking for them (and which were priced accordingly in an ironic twist on the original purpose.) Real, authentic Mexican food varies widely by region and will often surprise you in how much it differs from what we expect.
That being said, I'm happy that the SF Bay Area has the best AmeroMex (what the rest of you call Mexican) bar none. Any of you fools come to San Francisco, go to Taqueria Cancun on 19th & MIssion and spend $5 and walk out fat and very, very happy.



