Online, the video took on a vibrant life of its own. A meme using the hashtag #BBQBecky went viral, with the image of the woman appearing behind President Barack Obama in the White House, as a guest at the Last Supper, behind Martin Luther King at the March on Washington and on the bus with Rosa Parks.

The woman was also parodied this past weekend on “Saturday Night Live,” where she was played by an unsmiling Aidy Bryant. Attempts to reach the woman who reportedly called the police were unsuccessful.

Ms. Cortez said she saw the video and wasn’t surprised, given what she described as systemic racism in the town she grew up in. So, she sent a message to a few friends asking them to meet her at Lake Merritt for a barbecue.

“I wanted to deal with my lack of shock,” she said.

Now, after the overwhelming response from her community, she hopes to hold similar picnics throughout the summer.

For many in Oakland, Sunday’s barbecue was a reminder of days gone by, when the city hosted the Festival at the Lake in the 1980s and 1990s for a celebration of Oakland arts, music and culture. The festival was discontinued in 1997 because of budget cuts, concerns about public safety and low attendance.

“A lot of elders came up to me and said, you made me feel like it was the 1990s again,” said Jhamel Robinson, a graphic designer who was one of the organizers of the event.