First of all, to prepare the potato krapfen, cook the potatoes, still with the peel, in plenty of cold water for about 40 minutes. They must be well cooked.
At this point let’s peel them, still hot, and pass them in the potato masher; then let the mixture cool down by spreading it out on a pastry board.
Combine the previously sifted flour, eggs, yeast dissolved in a little warm water, grated lemon zest, melted butter, sugar, salt and mix everything well. Let the dough rise in a floured bowl covered with a cloth until it has doubled in volume.
When the dough has doubled, roll it out on a floured pastry board and work it by spreading it and flattening it until you get a 2 cm thick sheet.
With a 7-8 cm round pastry cutter we make many discs that will become our potato krapfen; then sprinkle them with flour and cover them with a cloth; then let them rise for about 30 minutes.
Then heat abundant peanut oil. Fry the potato krapfen in a pan or in a deep fryer a few at a time and when they are swollen and golden brown, drain them with a slotted spoon and place them on absorbent paper to remove excess grease.
Sprinkle the potato donuts with granulated sugar and leave to cool.
Useful tips:
If you don’t have a pasta cutter, you can use an upside-down glass to make the discs. If you prefer, you can sprinkle with powdered sugar instead of granulated sugar.