Combine all the ingredients in the bowl of your mixer.
Mix with the dough hook for 4 minutes at the lowest speed then 6 more minutes at second speed.
The dough should look smooth and be elastic. Depending on your mixer, it may take longer than 10 minutes. Just keep an eye on the dough and knead it until elastic.
Gather the dough into a ball then cover with bowl with plastic wrap. Allow to rest and rise for 40-50 minutes or until double in volume.
Transfer the dough on a floured working surface and roll it into a sheet that has about 1cm thickness.
Cut out your donuts using a big round cutter and a small cutter for the hole.
Heat up a few cups of oil in a saucepan. 160℃ should be enough to properly fry the donuts.
Place a few donuts in the hot oil and fry them on each side for 1-2 minutes.
Remove on paper towels then quickly, while still hot, roll the donuts in powdered sugar or granulated sugar for more texture.
Notes
*Bake the sweet potatoes prior to making the dough. You can easily substitute for pumpkin puree, in which case I recommend you add a touch of cinnamon as well.