Savory tarts are the well-kept secret of many country bakers. In a shop window, you may be dazzled by rows of open-faced fruit tarts, but a closer look usually reveals a plump, savory offering tucked away to the side, which seems to be selling well. In Alsace, you will see Zewelwai, a creamy onion version of quiche. Northerners seize on hefty slices of Flamiche with half-hidden fillings of leek or an odorous washed-rind cheese such as Maroilles. In Provence, it is likely to be Pissaladière, packed with onions and pungent with anchovy. As for quiche itself, everyone from the baker to the charcutier to the gourmet pastry shop has a trademark version. Such savory snacks are big business in France.