I’m a professional chef, and up until three years ago, I had no idea what barbacoa really meant.

I thought I did. I’d eaten my fair share of “barbacoa” at Chipotle, where its shredded-beef burrito was my splurge order. But on a tour of Xochimilco, a tapestry of canals and artificial islands that was once a major source of local produce for Mexico City, Paco, my tour guide, took me to his favorite barbacoa stall, where we were greeted with