San Diego de la Mesa is a tiny pueblo in the Mexican state of Puebla; the best guess is that 1,000 people live there. Almost all of them are involved in making mezcal, the smokey liquor made from the maguey plant. It's a labor-intensive, arduous task and it's led by maestro mezcaleros--master mezcal makers who may need ten years to learn all that's necessary to make the pueblo's artisanal mezcal.