By 11:30 a.m. Sunday, a meaty, righteous aroma wafted up from hundreds of grills set up around the northeastern shore of Lake Merritt. Oakland barbecue stalwart Everett & Jones was flipping yard-long racks of ribs to give away. Vendors of skateboard decks airbrushed with the greats of African American history set up next to political organizers calling out for registered voters. BBQ’n While Black was barely getting started.

Three Sundays before, Kenzie Smith and Onsayo Abram had fired up their Weber on the same strip of lawn. They had set up the cooler, the folding table and a couple of folding chairs when a white woman approached the two African American men to complain that they were using a charcoal grill in a non-charcoal-grilling area.

Then she called the police and stood there for two hours, sunglasses blocking out her gaze, face stern, cell phone glued to her ear. About 90 minutes into the one-woman standoff, Michelle Snider, Smith’s wife, took out her own phone and filmed herself attempting to talk to the woman. She was still filming when a police officer arrived and the confronter broke down sobbing, telling the officer that she was being harassed.

After Snider posted the video to YouTube, it racked up hundreds of thousands of views. The face of “BBQ Becky” — “Becky” is a snide term for a white woman — became a meme on social media. The image was manipulated so she appeared to officiously report Rosa Parks sitting on the bus, President Barack Obama occupying the Oval Office and Meghan Markle marrying Prince Harry. Laughter fused with fury as Whoopi Goldberg and “Saturday Night Live” weighed in.

BBQ’n While Black organizer Logan Cortez, a first-grade teacher in Oakland, saw the video shortly after it was posted. “I wasn’t surprised,” she said. “And the fact that I wasn’t surprised bothered me.”

Inspired by 510 Day, an anti-gentrification celebration at the lake on May 10, she sent a Facebook event invitation for five to seven friends, asking them to join her in barbecuing in the same spot.

Her friend Jhamel Robinson designed an electronic flyer and amplified the event notice on Instagram. Next thing they knew, Robinson said, it had been shared 2,500 times. DJs volunteered to spin. Others offered to act as security and clean up.

Unwilling to provoke any other outrage from neighbors, the two 28-year-olds applied for city permits for the barbecue, spending $700 of their own money.

“It’s the community coming together in a positive way as a reaction to what’s going on,” Robinson said. “Instead of tearing up the city, we want to come together in love and unity. And party.”

“Unlike the civil rights movement, we aren’t fighting for our rights,” Cortez added. “Now we’re fighting for the right to simply live within the law.”

Rosalind Bosset, whose family was grilling up veggie patties and asparagus by the lake on Sunday, said the video “broke my heart.”

Like many native Oaklanders, she had always seen the lake as a welcoming spot. She remembered, as a 12-year-old in the early 1970s, when the entire 3½-mile shore was occupied by African American families spending the afternoon outside grilling. As an adult, she walked around the lake with her grandmother until the older woman was in her 80s. So it was particularly hurtful for someone to stereotype black people in the city’s communal backyard.

Some of the participants had set out blankets and speakers, even incense. Others, like Cristhian Delgadillo, had shown up at 8 a.m. with a full rig. Delgadillo was carefully attending a smoker where he was cooking fish, sausages, frog’s legs and goat hearts over his special blend of smoked wood chips and herbs. The city of Oakland employee pointed out a Department of Public Works truck circulating, ready to pick up trash and any coals people deposited on the curb.

Smith could be spotted at the park, circulating among friends, but refused all interview requests from the many TV cameras and notebook scribblers documenting the barbecue.

Amir and Lisa Aziz, who live two blocks from the site, bicycled by to check out the scene. Lisa Aziz is a member of the Cleveland Heights neighborhood watch, and the couple recognized “BBQ Becky” as a neighbor. “If you saw the emails that circulated about this, then you’d know she’s not alone,” Lisa said.

Justin Ford, who said he was Smith’s cousin, had claimed a spot early in the morning for a table selling his Oakland’s Own hats. “This is a microcosm of what is going on in Oakland,” Ford said. As much as Oaklanders have to accept gentrification, he added, “We want to celebrate Oakland being the most diverse city in the country.”

Most people said they were there to spend the afternoon, and the crowd continued to grow in the afternoon.

By 2 p.m., a quarter-mile curl of the lake had blossomed into a street party several thousand strong. Half clasped paper plates and Solo cups; the other half filled the sidewalk, surveying the scene and calling across the green to friends. Motorcycles, dancers, drummers, spinning selfie-takers and food trucks all showed up to transform the site of an outrage back into a celebration of a sunny Sunday.

Robinson, one of the organizers, was born and raised in Oakland but had recently moved to Sacramento, driven out by rising rents. He sported a tank top his Real Oakland brand was selling. “My hope for this event is for people who are true natives of Oakland to come together and show what I would consider the new Oakland, the gentrified Oakland, that we’re still here, we’re not going anywhere,” he said.

Jonathan Kauffman is a San Francisco Chronicle staff writer. Email: jkauffman@sfchronicle.com Twitter and Instagram: @jonkauffman