San Telmo, Buenos Aires – a mecca for tourists Sometimes a new place just reaches out and takes you into its arms. One minute, Carla Jacome was part of the crowd of tourists taking in a Sunday morning tango demonstration at San Telmo’s Plaza Dorrego. The next, she was part of the show, gliding through the unfamiliar steps in the firm embrace of tango maestro Osvaldo Boo, the picture of suave elegance in a dark grey suit, fedora and white scarf. Welcome to San Telmo, an aging downtown barrio that…