Zwiebelplatz for bbd#07
Potato-rye flatbread with onions
2 cups (275 g) (Yukon Gold) potatoes, peeled and diced
2 tbsp (18 g) kosher salt
2 tbsp (15 g) yellow cornmeal (whole grain, stone ground)
1 cup (102 g) dark rye flour
3 cups (400 g) bread flour (King Arthur brand) or as needed
1/2 tbsp (6 g) sugar
1 tsp (4 g) active dry yeast dissolved in 2 tbsp (30 ml) warm water
2 tbsp (30 g) unsalted butter
1 onion, sliced paper-thin
1-2 tbsp (15-30 g) butter
Cook the potatoes in boiling water until tender. Strain and reserve cooking water. Mash the potatoes and place them in the bowl of a stand mixer. Measure 1-1/2 cups of the potato water (add extra water if necessary to have 1-1/2 cups) place in a saucepan and mix with the salt and cornmeal. Bring to a boil, then take off the heat and add the butter, stirring until it is melted. Pour the mixture on the mashed potatoes and mix briefly. Let cool.
Once the potato mixture is cold, add the flours and then the yeast dissolved in 2 tbsp (30 ml) warm water. Knead until the dough develops, about 7 minutes at low speed. The dough will be tacky, if too sticky and wet you may need to add a little more bread flour. Don’t add too much, the dough should be tacky because of the rye and potatoes.
Place the dough in a buttered bowl, cover and let it rise—preferably overnight in a cool place. The refrigerator might be fine, but a room with a temperature of 50°F (10°C ), such as a basement, is best.
Preheat the oven to 450°F (230°C), place a rack in the middle slot.
Once the dough is fermented, take it out of the bowl and delicately, without kneading it, stretch it and flatten it with the palms of your hands to form a thin rectangle. Place it in a buttered jellyroll pan (11 x 16 x 0.5-inch—28 x 40.5 x 1.27 cm), spread on the surface the onion slices and dot with butter here and there.  (click on picture to enlarge).
Notes: it is important that the potatoes are mashed while still hot and mixed with the flours when cold. Warm potatoes make the dough gooey and tend to absorb lots of flour, ruining the final result.
Mashing the potatoes with a fork so that small pieces remain whole is better than using a potato ricer—the potato bits are tasty to find in the finished bread.
From the original recipe by Florence Kreisler Greenbaum
In: “The International Jewish Cook Book: 1600 Recipes According To The Jewish Dietary Laws With The Rules For Kashering: The Favorite Recipes Of America, Austria, Germany, Russia, …”,1919—USA