The first step in the long crawl back will be setting standards to protect workers and diners. “The most pragmatic thing we need to figure out right now is safety protocol,” said David Chang, the restaurateur and media star. “We are all asking for that, and no one really knows.”

The questions pile up fast. Should you rely on disposable paper menus, or is wiping down plastic-covered ones safe? What kind of thermometers are best to check employees’ health, and will diners submit to temperature checks? Can air-conditioning spread the virus? What is a restaurant’s liability if a customer gets sick? How does a sommelier taste wine while wearing a mask, and how do you rewrite a menu so cooks can stay safe in the tight confines of a restaurant kitchen?

“Once you go down this rabbit hole, it’s going to make your brain bleed,” Mr. Chang said.

He, like many chefs, is looking to restaurants in Asia, where several cities have begun to allow diners to return.