Three high double-stops from the guitar announce the song’s opening. Two trills and a rapid slide down the neck, and the crowd explodes into whoops and cheers. A series of meditative, arpeggiated chords. A pause. Then the guitarist launches into a fast waltz rhythm, percussive and full of manly swagger, in which he’s joined by a percussionist seated atop a cajón—a huge wooden sounding box—and another holding a cowbell.