Sergio Mendoza says his grandfather was playing in a Mexican military band at the age of 7 in Sonora. That's how far Mendoza's musical roots go back, and his performances at SXSW this year reflect those roots with a vision that would have made his grandfather proud. Mendoza says he's fascinated by 1950s-era big-band mambo bandleader Perez Prado; he faithfully reinterprets Prado's style, but when he adds a surf guitar, the sound becomes fresh and new. It grooves like a runaway train