Please read About Doughnuts.
Prepare:
Whisk together thoroughly in a medium bowl:
Beat in a large bowl, with an electric mixer at high speed, until foamy, about 1 minute:
Gradually add and beat until thick and creamy:
On low speed, add and beat until blended:
Beat in the riced potatoes. Using a large spoon, stir in the flour mixture. The dough will be very soft. Wrap in plastic and refrigerate for at least 2 hours and up to 24 hours.
Roll out, cut, rest, and fry as for Cake Doughnuts. Drain briefly on a baking sheet lined with paper towels, then, while still warm, toss in a bowl with:
Or let cool and glaze with: