The name is first attested in the 19th century, and is a corruption of the term en surprise, which is used in French cuisine for all types of croquettes or pieces of meat covered with breadcrumbs.[4]
Originally, they were filled with chicken giblets, mincemeatorprovatura (a type of cheese from Lazio),[1] now also with a piece of mozzarella; the whole morsel is soaked in egg, coated with breadcrumbs and then fried (usually deep fried).[1] They are closely related to Sicilianarancini and the Frenchcroquettes, sometimes called croquettes en surprise,[5] that can be made with rice.[6]Supplì can be also prepared without tomato sauce (supplì in bianco, which means 'white-style supplì').
They are usually eaten with the fingers: when one is broken in two pieces, mozzarella is drawn out in a string somewhat resembling the cord connecting a telephone handset to the hook. This has led to these dishes being known as supplì al telefono ('telephone-style supplì', in reference to cables).[7]
Supplì were originally sold at friggitorie, typical Roman shops where fried food was sold. Now they are commonly served in most pizzerias all around Italy as an antipasto.