Across the border in Alsace the same dish is called tarte flambée, and the classic topping of crème fraîche, onion and bacon is the same on both sides.
A paper-thin dough is spread with crème fraîche, then scattered with onion and bacon lardons and baked briefly at very high heat until the edges char and blister. Pfalz wine-village stands and street festivals cut it into strips and sell it by the piece.