The trend: big-time chefs launching modern Mexican joints with the tastiest tacos this side of the Rio Grande. Last fall, Sean Brock opened Minero in Charleston, while John Besh and Aarón Sánchez rolled out Johnny Sánchez in NOLA. Alex Stupak's Empellón Al Pastor in Manhattan has earned huge raves. Now the world waits to see what comes of Danish überchef René Redzepi's Mexican infatuation.