Tablier de sapeur is a typical dish of the city of Lyon. It owes its name to a military governor of Lyon in the time of Napoleon III, Marshal de Castellane. A lover of tripe and fine cuisine, he gave the dish its name meaning "fireman's apron" as it resembled the leather aprons that firemen wore during difficult jobs.
It's actually a steak made of tripe marinated in white wine, then breadcrumbed and fried. Beef caul is generally used to make this dish. The meat must have marinated for several hours in white wine, lemon juice, oil, mustard, salt and pepper, before being dipped in beaten egg then breadcrumb. The preparation is then fried then oven-baked. This gives a very tender dish that is generally eaten with sauce tartare, gribiche sauce or mayonnaise, and fried potatoes.