http://offthegridsf.com/
They happen almost everyday now. If your on Instagram, that is the best way to find out where its happening. They generally post their location and what food trucks will be there daily.
If your up near Infineon Raceway there is a good Puerto Rican restaurant in downtown Santa Rosa called El Coqui. I believe its another 20 mins north of Infineon Raceway.
http://www.elcoqui2eat.com/