Ersi Arvizu is "Muy Fifí" on Ry Cooder's latest CD, Chavez Ravine. I don't know why, but the song and the CD are not available on iTunes. You can hear a snippet here, and of course at Amazon. According to this review on Rootsworld, Cooder tracked down Arvizu, who had earlier sung with the groups The Sisters and El Chicano, in Arizona, where she was working as a Fedex driver.