Craving a burger? Head to San Francisco’s Dolores Park Sunday to taste the Silicon Valley-built “Impossible Burger,” designed in a lab.

And best of all, it’s free.

Redwood City’s Impossible Foods will be offering vegan versions of the traditional all-American beef patty from its food truck from noon to 4 p.m. — first come, first served. The truck will have limited supplies and may run out early.

This “Impossible Burger” aims to be something different than the bland and traditional beans-and-grains veggie burger.

The burger was made by reverse-engineering the texture and taste of meat — using a lab-designed combination of proteins, fats and amino acids derived from wheat, soy, coconuts, potatoes and other plant sources.

Impossible Foods is a private company with financial backing from Khosla Ventures, Bill Gates, Google Ventures and others. It was founded by Dr. Patrick O. Brown, a former biochemistry professor and Howard Hughes Medical Institute investigator at Stanford University.

Humans have been eating meat for millions of years. But there is a growing movement to create food through technology — creating meat-like properties, without killing an animal. These products also reduce greenhouse gas emissions and contain no hormones, antibiotics, cholesterol or slaughterhouse contaminants.

Other companies include Beyond Meat, with a plant-based “Beyond Burger” and Hampton Creek‘s canola oil-based Just Mayo.

Memphis Meats grows real meat in small quantities using cells from cows, pigs, and chickens. Google co-founder Sergey Brin, who provided $330,000 to fund the company’s first cultured hamburger, described cultured meat as a technology with “the capability to transform how we view our world.”

If supplies run out on Sunday, the Impossible Burger is not yet at supermarkets but can be ordered at San Francisco restaurants Jardinière and Cockscomb restaurant, as well as Crossroads Kitchen in Los Angeles and Momofuki Nishi in New York City.