German Onion Tart

Make the dough: Heat oven to 375 degrees F. Lightly coat 2 baking sheets with oil and set aside. Combine 1 cup flour, yeast, sugar, and 1/2 teaspoon salt in a large bowl. Melt 3 tablespoons butter and whisk it and 1 egg together in a medium bowl. Slowly pour the butter-and-egg mixture into the flour mixture while mixing with a wooden spoon. Add the water and continue mixing until a shaggy, wet dough forms. Mix in the remaining flour and transfer dough to a floured work surface. Knead for 10 minutes until smooth but still somewhat tacky. Transfer dough to a lightly oiled bowl, cover with plastic wrap, and set in a warm place to rise until doubled in volume -- about 1 1/2 hours.

Make the onion topping: Place the onions and remaining butter in a large skillet and cook over medium-low heat, stirring occasionally, until golden brown. Cool completely. Whisk together the remaining egg, sour cream, white pepper, and remaining salt. Mix with the cooled onions.

Bake the tart: Punch down dough and divide it into 6 equal portions -- each about the size of a lemon. Press and stretch dough with fingertips to form six 8-inch circles and crimp the edges to form a ring. Place the 6 dough circles on each prepared sheet and top each with the onion mixture, leaving 1/2 inch free at the edges. Lightly sprinkle caraway seeds over tarts. Bake on the middle shelf of oven until golden brown and onion mixture sets -- about 10 minutes. Serve warm or at room temperature.