Saying the City Council stuck its beak where it didn't belong, a restaurant association sued the city Tuesday in hope of making foie gras legal again.

Meanwhile, a handful of chefs said they will continue to serve the duck and goose liver delicacy — it just won't appear on the bill.

"The law says we can't charge for it. It doesn't say we can't give it away," said Michael Tsonton, chef and partner at Copperblue.

The ban was approved by the city council in April and implemented Tuesday. Animal rights activists contend that the production of foie gras — which involves force-feeding ducks and geese to enlarge their livers — is inhumane.

The lawsuit showed that chefs aren't content muttering in their kitchens about the ban. A related news conference featured several white-jacketed chefs standing before a banner that read "Freedom Of Choice On The Menu."

The suit, filed by the Illinois Restaurant Association and one restaurant, argues the council overstepped its authority. Aldermen may agree that the production of foie gras is inhumane, but they can't ban it because none of the force-feeding occurs anywhere near Chicago or even Illinois, the suit says.

The lawsuit followed months of complaints, fund raisers, petitions and special events. In a show of solidarity Tuesday, restaurants that don't typically serve foie gras, including one pizzeria, gave diners what may be their only chance to utter the phrase, "Mushroom, sausage and foie gras pizza, please."

Chefs have called the ban an attack on their right to choose what kinds of dishes they want to create and an attack on the rights of consumers.

They also say the ban will cost more than $18 million a year in lost sales, tax revenues and tips — and may even dissuade chefs from opening restaurants here.

"Whether the treatment of animals in Canada, France or New York leading to the production of foie gras is or is not humane is not a problem suitable for legislation by the City of Chicago, let alone a substantial Chicago problem," the lawsuit argues.

A spokeswoman for the city's law department said the argument that the city can't regulate a product because it is not produced here simply does not fly.

"Fireworks, guns, we regulate all those things and they aren't produced in Chicago," said Jennifer Hoyle, who said she had not seen the lawsuit.

Alderman Joe Moore, who led the effort to ban foie gras, agreed. "We feel that this is a constitutional ordinance and an ordinance well within the city's power to enact," he said.

More than a dozen countries, mostly in Europe, have banned production of the fois gras, pronounced fwah-GRAH and French for "fat liver," on the grounds of cruelty.

Attorney Barry Rosen, who represents the Illinois Restaurant Association, said he expects to file a motion for a preliminary injunction in the next few weeks.

As for restaurants concerned that diners will go elsewhere, putting foie gras in garnishes may be a solution, at least until the legal battle plays out.

Didier Durand, chef and owner of Cyrano's Bistrot & Wine Bar, plans to do just that.

"On the check you won't see foie gras," Durand said. "You will see roasted potatoes $16."