Steps

• To prepare the potato doughnuts, wash the potatoes well, scrubbing the skin thoroughly, and put them in a pot. Cover with water and bring to a boil. Boil until the potatoes are softened, test by piercing with a fork. Cooking time varies depending on the size of the potatoes, approximately 25 to 40 minutes from boiling.

  When the potatoes are cooked, remove them from the water, let them cool for about ten minutes, peel them, and mash them with a potato masher. Then let them cool slightly.

  

• In the meantime, prepare a pre-dough by placing 1/3 cup of flour, 1/4 cup of warm milk, and the yeast in a small bowl. Mix well with a fork until you get a smooth and very soft mixture, and let it rest covered for about 1 hour, which will be about the time it takes for the potatoes to cook and cool.

  After the pre-dough resting time and the potatoes have cooled slightly, put the remaining all-purpose flour, the entire pre-dough, sugar, and the grated lemon zest in the bowl of a stand mixer. Mix.
  Add the warm mashed potatoes and turn on the mixer. Then add the remaining warm milk, followed by the eggs and salt. Knead until you obtain a homogeneous dough.

  At this point, add the butter cut into cubes, little by little, and continue kneading until the dough is well developed, i.e., it detaches from the bottom and sides of the bowl and is completely wrapped around the hook, appearing smooth and elastic.

  Form a ball with the dough and let it rest covered until doubled, in a warm place away from drafts. This will take about 2.5 hours.

  

• Once the dough has doubled in volume, divide it into 12 equal pieces with the help of a scale. Take one piece at a time and, on a lightly floured surface, form a smooth rope about 12 inches long. Then join the two ends, overlapping them slightly and pressing at the point of contact, so they don’t open during frying.

  Place on a baking tray lined with parchment paper and let rise covered for about 45 minutes.

  

• After the additional resting time, heat the oil in a large pot until it reaches 320°F.

  In the meantime, cut the parchment paper on which the doughnuts are placed into rectangles, so that each doughnut is on an independent piece of parchment paper. Prepare a deep plate with a few tablespoons of sugar.

  When the oil has reached the right temperature, depending on the capacity of the pot, dip 2-3 doughnuts into the oil along with the parchment paper and fry for 2 minutes on each side. You will see that when you turn the doughnuts, the parchment will detach on its own, and you can remove it from the oil with the help of tongs.

  When the doughnuts are nice and puffy and golden, remove them from the oil with a slotted spoon and place them for just 2 minutes on kitchen paper to absorb the excess oil. Then roll them in sugar while still warm on all sides. Make sure the doughnuts are still nice and hot when you roll them in the sugar, otherwise, it won’t stick.

  Once coated in sugar, place your potato doughnuts on a rack and let them cool, or enjoy them warm.

  Potato doughnuts, like all fried foods, are best enjoyed freshly made or eaten on the same day. If you have leftovers, you can freeze them, or, if needed, store them in an airtight container for a day. In this case, I recommend reheating them slightly before enjoying, so they taste almost freshly made.