410 ILCS 650/10.1

It is unlawful for any restaurant to list a particular food product for sale on its menu when such product is not actually sold to consumers, but an imitation or substitute food product is served in its place. If such imitation or substitute food product is served, the menu shall clearly state that the product is imitation or the name of the substitute product. For purposes of this Section "menu" means a list of food products offered for sale at a restaurant.