Mr. Marcus said he hoped to have guidelines in place by June. Until then, he said, restaurateurs who wanted to use sous vide need to have a food scientist draw up a Hazard Analysis and Critical Control Point plan, a procedure laid out in the federal Food Code.

But many chefs who use sous vide say they have studied it with pioneers in the field, like the French chef George Pralus, who have carefully developed procedures for sous vide safety.

"It's a safer, more precise way of cooking," said Jonathan Benno, chef de cuisine of Per Se, at the Time Warner Center. Mr. Benno spent much of Tuesday developing a plan with the sous vide guru Bruno Goussault, a food scientist who works with the company best known for industrial-scale sous vide operations, Cuisine Solutions in Alexandria, Va. City officials have yet to approve that plan or any others.

Thomas L. Gregg, the president of Cuisine Solutions, which prepares sous vide meals for airlines and has taught many Manhattan chefs how to use the procedure safely, said he had never heard of such a crackdown before. But he said that like any technique, it could be dangerous without the proper training. "Sous vide has become very popular, and the health department is sending a signal out that you need to have the proper protocols in place," Mr. Gregg said.

The technique has also become popular with adventurous home cooks, some of whom have been using the sorts of vacuum-sealing devices sold on television, like Seal-a-Meal. Thomas Keller, the chef at Per Se and at the French Laundry in Yountville, Calif., will be coming out with a sous vide cookbook soon.

The technique was first developed in France in the late 1960's. Even as it became widely used by airlines, hotel chains and other institutions, concerns were raised about possible bacterial contamination. But this seems to be the first time that health concerns have been raised about its use in restaurant kitchens.

Officials say they began looking into sous vide last summer after an article in The New York Times magazine described how Mr. Pralus and Mr. Goussault brought sous vide out of the clinical realm of industrial food production and into the controlled chaos of restaurant kitchens.