“It can seem pretty arbitrary,” said Andrew Baber, who runs Off the Grid’s consulting arm. “They’ll deny your permit because there’s an unused air-conditioning vent like 500 feet away.”

By contrast, Off the Grid vendors do not need a D.P.W. permit, as its event spaces are preapproved for mobile food vending. And Mr. Cohen says health and fire licenses are expedited for his clients.

Bobby Hussein, owner of a soon-to-open truck, Phat Thai, had heard horror stories about how long it could take to obtain permits. “City Hall knows all these Off the Grid guys.” he said, “It took four days to get my permits.”

“You can try to make it on your own,” said Bevan Dufty, the former San Francisco city supervisor who has worked with Mr. Cohen on mobile food legislation. “But why would you want to?”

This help is not free, however. Off the Grid charges $50 per event, plus 10 percent of each vendor’s earnings. Additional advice on starting a new mobile food business costs $150 per hour.

In addition, before new trucks are allowed to join, Mr. Cohen’s team taste-tests all the food, reviews the aesthetics of the truck and makes suggestions or demands. “We don’t book anyone whose food we don’t like,” Mr. Cohen said. “And if we have concerns with how you’re running your business, we’re going to be brutally honest.”

Not all vendors are interested in subjecting themselves to these rules. Meg Hilgartner is co-owner of Twirl and Dip, an organic soft-serve ice cream truck. She worked Off the Grid events for three months while she was waiting for a permit in Golden Gate Park. But since the park permit came through, Ms. Hilgartner has not returned. “If you’re with Off the Grid, you’re managed by Matt Cohen and his team,” she said. “If it’s rainy or foggy, I want to go home!”