A favorite for many Germans, it is known as Zwiebelkuchen in Germany.
Put flour in a large bowl, add the cubed chunks of cold butter and mix
together, then add the water slowly while mixing till the dough comes together,
till it is soft but try not to overwork it. There may still be chunks of butter
in the dough, which is good.
Sauté diced bacon in a pan till crisp, remove and place on paper towel. In the left over bacon grease sauté the onions until they are caramelized to a light golden brown color. Do this over medium heat making sure to stir occasionally so onions do not burn. Add caraway seeds and salt and pepper. Add bacon to the onion mix and place inside the dough lined pan, bake at 400 F for 20 minutes or until dough is lightly golden.
In a bowl mix egg yolks and sour cream. Pour over the onion bacon mixture and bake again for 10 to 15 minutes, until sour cream mixture is set. Remove from oven and let cool.
Shown in the picture is a tartlet cut into fours, two slices plated and garnished with a balsamic vinegar reduction for an appetizer. Zwiebelkuchen can be served for any meal whether large or small. As a meal it is usually served with a salad.