Which German savory tart is traditionally made with onions and yeast dough?

Zwiebelkuchen is the German savory tart traditionally made with onions and yeast dough.

The tart usually has a bread-like yeast crust covered with cooked onions, eggs, and cream or sour cream. Bacon is also common, especially in regional versions from southwestern Germany. It is baked until the filling is set and lightly browned.

Zwiebelkuchen is strongly associated with the autumn wine season in regions such as Franconia, Hesse, and the Palatinate. It is often served with Federweißer, a young, partially fermented grape wine.

It is different from Flammkuchen, whose thin crust is traditionally topped with crème fraîche, onions, and bacon. Zwiebelkuchen has a thicker, more substantial tart base and a softer filling.