Monday was a routine day for Grant Di Mille and Samira Mahboubian, the owners of the Street Sweets food truck, a mobile trove of croissants, cupcakes and cookies that got rolling last month.

The couple loaded the truck by 6 a.m., parked in front of the Museum of Modern Art at 7, traded hostilities with other vendors from 9 a.m. to 1 p.m., and were surrounded by police officers by 2.

“The police told these guys that nobody owns the streets. But it sure doesn’t feel that way,” said Mr. Di Mille, who called the Midtown North precinct — not for the first time — when a jewelry vendor set up shop directly in front of his sales window.

In four weeks of business, the couple has been threatened at the depot where they park the truck; cursed by a gyro vendor who said that he would set their truck on fire; told to stay off every corner in Midtown by ice cream truck drivers; and approached by countless others with advice — both friendly and menacing — on how to get along on the streets.

“I want to be a good neighbor,” Mr. Di Mille said. “But I am nobody’s fool, and nobody’s pushover, and I should not have to carry a baseball bat on my truck in order to sell cupcakes.”

In the last two years, upscale food trucks have swarmed the streets, entrancing New Yorkers with everything from artisanal Earl Grey ice cream to vegan tacos. These highly visible trucks, their outspoken owners and their followers on Twitter, Facebook and food blogs, have broken the code of the streets that has long kept a relative peace among food vendors.

Turf wars are nothing new for carts selling kebabs and cheap coffee. But the makers of thumbprint cookies, chicken-Thai basil dumplings, and crème anglaise are not happy about the sharp elbows that are part of the city’s sidewalk economy, or the murky bureaucracy that oversees the issuing of permits. (Six people were arrested on Tuesday on fraud charges related to food vending permits.)

These new culinary entrepreneurs, most of them with English as their first language and little fear of police or immigration authorities, say that they are on a mission to bring better street food to New Yorkers, and ready to bring dark corners of the business to light.