Signature dish

A signature dish is a recipe that identifies an individual chef. Ideally it should be unique and allow an informed gastronome to name the chef in a blind tasting. It can be thought of as the culinary equivalent of an artist finding their own style, or an author finding their own voice. In practice a chef's signature dish often changes with time or they may claim several signature dishes.

In a weaker sense, a signature dish may become associated with an individual restaurant, particularly if the chef who created it is no longer with the establishment. It can also be used to refer to a culinary region, in which case its meaning may be the equivalent of "national dish". In many cases, restaurants will base their menu development on tastes and styles which are unique to the restaurant's geographical location. Local produce, restaurant décor, and even the type of building you choose can all contribute to a larger yield by taking on local sensibilities. Emphasizing (an establishment's) connection to its location provides great marketing possibilities.

At its weakest, the term can simply mean "chef's specials" which are in no way unique or even particularly unusual.

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Wikipedia