This adaptation of an old French dish is a flat bread topped with a moist, creamy leek and bacon custard. The author thinks of it as a hybrid of Alsatian Flammkuchen, quiche Lorraine, and German Zwiebelkuchen, or onion tart. Inattention at two points of preparing it can ruin the topping; the author, Gudrun Riter, explains how to avoid disaster. She offers lighter variations at the end, as well as other ideas that speed preparation or adjust for seasonal preferences. Photos detail the crust construction and produce tips for selecting the tastiest leeks.