SAN FRANCISCO — Along with big-wave surfing and high-altitude ultramarathons, eating is an extreme sport here. Which explains why, on a recent Saturday night, Tipay Corpuz, 21, a technology specialist for Apple, took a break from blogging about her obsession with fried chicken and waffles to join 2,500 fellow food geeks at the Underground Night Market.

At this quasi-clandestine monthly event, a tribal gathering of young chefs, vendors and their iron-stomached followers are remaking the traditional farmers market as an indie food rave.

At midnight, the smell of stir-fried pork bellies was wafting through the Mission district. There was live music, liquor, bouncers, a disco ball — and a line waiting to sample hundreds of delicacies made mostly on location, among them bacon-wrapped mochi (a Japanese rice paste) and ice cream made from red beets, Guinness and chocolate cake.

In a sense it is civil disobedience on a paper plate.

The underground market seeks to encourage food entrepreneurship by helping young vendors avoid roughly $1,000 a year in fees — including those for health permits and liability insurance — required by legitimate farmers markets. Here, where the food rave — call it a crave — was born, the market organizers sidestep city health inspections by operating as a private club, requiring that participants become “members” (free) and sign a disclaimer noting that food might not be prepared in a space that has been inspected.