As local food movements sprout from Brooklyn to San Francisco, one organization towers over them as the perennial of the bunch. Founded in 1980 in Cambridge, Massachusetts, by anti-nuclear activists, Food Not Bombs is a loose collection of some 1,000 global chapters seeking to overturn governmental and corporate policies they believe undergird hunger in a world of abundance. Every week, volunteers cook vegan food and donate it to people in public spaces and at protests.

Food Not Bombs uses food to effect change. On October 16, World Food Day, the chapters are encouraged to serve vegan meals outside local McDonald’s franchises to draw attention to industrialized food production. March 26, 2011, marks the 30th anniversary of the first meal dished out by the organization. (Original members, dressed as vagrants, set up a soup kitchen outside a Bank of Boston stockholders meeting to protest financing of a local nuclear power plant at the expense of pressing social issues.) Food Not Bombs will honor the date with an event called Bake Goods Not Bank Bailouts Global Day Of Action, in which members will distribute free vegan meals in front of banks.

A philosophy of nonviolent action for social justice gives the organization a political edginess not always palatable to locavores who are more inclined to fight for the perfect heirloom tomato than against corporate food conglomerates. “It’s urgent that we directly challenge the system,” says Keith McHenry, co-founder of the organization, speaking on his mobile phone as he drove across West Virginia. In his recent travels, McHenry says, he’s seen more and more families — casualties of the mortgage crisis and recession — search out Food Not Bomb’s hot meals.

Every Sunday evening, the Los Angeles chapter dishes up vegetable stew, brown rice and pinto beans. In the afternoon, a volunteer crew of graying activists, cyclist punks and the occasional suburban helper convene in one Silverlake kitchen or another to cook. Ingredients are donated from across the metropolitan region. Volunteers pick up unsold produce from the Hollywood Farmers Market. Whole Foods in Pasadena contributes leftover baked goods. Oh Happy Days, a health-food store in Altadena, has religiously donated 25 pounds of onions, rice and beans each week for the past six years.

Weekly, 200 to 300 people show up for food at two outdoor sites, Pershing Square Park and Skid Row. In Pershing Square — designed by the architect Ricardo Legorreta and landscape architect Laurie Olin in the early 1990s, and filled with colorful features, such as a 10-story purple bell tower — Food Not Bombs volunteers set up a buffet atop a long concrete bench. The simple act of taking over public space to serve plates of stew is not without controversy. In 1999, Los Angeles police arrested volunteers in the park for encroaching on a permit held by organizers of a seasonal ice rink. A successful ALCU suit filed against the LAPD defended Food Not Bombs’s First Amendment rights and set a precedent that has smoothed its course of activism.

On St. Julian Street, otherwise known as Skid Row, Food Not Bombs sets up folding tables on the sidewalk outside the Union Rescue Mission. Here, according to a 2009 report by the Los Angeles Homeless Services Authority, 3,800 indigent people, 9 percent of the city’s total homeless population, live in a 50-block area. “Seeing tent cities on Skid Row was shocking. You don’t get desensitized to it,” says Joshua Haglund, a longtime Food Not Bombs organizer. Recently, photographer Monica Nouwens documented members of the Los Angeles chapter as they cooked and served. Her images, shown here, reveal the simple comfort and solidarity a hot meal can offer.