Proof the yeast. In a large bowl, combine one tablespoon of the granulated sugar with the yeast and the warmed (110-120°F/43-46°C) soymilk. Whisk together and set aside for 10 minutes to allow the yeast to proof. If no bubbles/foaming has appeared, the yeast isn’t active and you’ll need fresh.
Make the dough. Into a large bowl of a stand mixer with the dough hook attachment, add the remaining ingredients of mashed potato, canola oil, sugar, vanilla, salt, and the bread flour. Mix on low speed for 2 minutes to allow the ingredients to combine, then, mix on medium speed for the next 6 to 8 minutes to allow the dough to form. This dough is very sticky so you may be tempted to add more flour. Only add flour in the final 2 minutes of mixing if necessary.
First Rise. Gently shape the dough into a ball and place it into a lightly greased bowl. Place the bowl, covered with a clean kitchen towel, in a warm spot in your kitchen and let it rise for about an hour, or until doubled in size.
Shaping + Second Rise. When the dough has doubled in size, place the dough onto a lightly floured surface and divide the dough into 12 equal pieces, about 90 to 100 grams in weight. You don’t need to be super precise with this. Roll each donut into a tight dough ball in your hands and place on a parchment lined baking sheet, 6 donuts to each sheet. Allow them to rise, uncovered, for 20 minutes while the oven preheats.
Preheat the oven to 375°F/190°C.
Final Shaping. Right before the donuts are ready to go in the oven, use a rolling pin to gently give each donut their final shape. Gently roll into an oval, making sure not to push down hard at all. Brush the top of each donut with more canola oil.
Baking. Bake the donuts in the oven for 16 to 18 minutes or until golden brown and they have reached an internal temperature of over 195°F/90°C.
Rolling. When the donuts are hot from the oven, roll them in more granulated sugar for a bakery style donut. Allow the donuts to cool so they are able to be handled. Before filling, roll the donuts again in powdered sugar until they are totally covered.
Filling. Using a chopstick or knife, make a hole in the side of each donut, wiggling slightly to make a space for filling. Fill each donut with the filling of your choice, using a pastry bag to make the filling easier. Repeat for each donut. Serve and enjoy!
