What Comes Next for the Most Empty Downtown in America

For the optimized office worker looking for the trifecta of fast, healthy and filling, few meals are more efficient than a pile of veggies and some dressing swirled with tofu or grilled chicken. Unfortunately, the aspirations of a salad are often dashed by the difficulty of making one that is actually good. The ingredients come from every corner of the supermarket, and if they aren’t combined in the right proportions, or if they are made too far in advance, every bite is a drag.

Ms. Silverglide, 42, the chief executive of Mixt, tried to solve this problem with a setup in which customers proceeded down a counter and called out ingredients like grilled chicken and roasted brussels sprouts while stipulating exactly how much dressing they wanted. She said the naysayers of the time told her that there weren’t enough salad eaters to sustain her company, or that only women would eat there.

Instead, lines extended down the block, and Yelp’s users gave the business three and a half stars. People like Mike Ghaffary discovered a healthier kind of lunch in a restaurant where customization was encouraged.

Mr. Ghaffary is a former Yelp executive and serial optimizer who went to Mixt in search of a vegan meal that was high in protein and low in sugar. The salad he came up with paired lentils, chickpeas and quinoa with greens and a cilantro jalapeño vinaigrette.

Over the next several years, as Yelp grew and went public, Mixt thrived alongside it, adding a dozen locations through downtown and other city neighborhoods. Mr. Ghaffary became something of a Mixt evangelist (“He was very proud of the beany salad he came up with,” Mr. Stoppelman said) and ordered his vegetal concoction so frequently that the salad was added to the permanent menu and still sits on the board under the name “Be Well.”

In the city, however, well-being was taking a hit.

The tech companies that San Francisco had tried so hard to attract were now the target of regular protests, including some by demonstrators who at the end of 2013 began blocking commuter buses from Google and other companies to show their rage at rents that now sit at a median of $3,600. This was an opening gesture in what would become an ongoing debate about gentrification and the effect of tech companies on the city — a debate that played out in arguments over homeless camps, votes to stop development and countless more protests.

All of this was rooted in the cost of housing, which had been expensive for decades but had morphed into a disaster. A local government that had all but begged tech companies to set up shop there was now pushing a raft of new taxes to deal with its spiraling affordable housing and homelessness problems. In 2017, the year the Salesforce Tower eclipsed the Transamerica Pyramid as the city’s tallest skyscraper, Mr. Florida published another book. It was called “The New Urban Crisis.”