Boil the potatoes in their skins. Dissolve the yeast in the salted, lukewarm milk and let rise in a warm place for 10 minutes. Peel the potatoes and pound them while they are still lukewarm. Sift the flour into a bowl. Make a well in the middle and pour the yeast milk into it. Add the potatoes and oil and work into a smooth dough. Sprinkle thinly with flour and cover with a kitchen towel and let rise in a warm place for about 1 hour until twice the size.
Fill a pan about 6 cm high with oil. Tear off a piece of the risen dough, shape it into a flat cake about 2 cm thick and place in the hot oil. Bake until golden in an open pan, then turn carefully and bake the other side until crispy. Salt and consume hot.
If you like, you can coat your flatbread with sour cream, cheese or garlic. The imagination knows no limits!