1-First Step: Mise en place and dry ingredients
Sift together the dry ingredients to avoid any lumps and to lighten the flour. In a medium bowl, sift 2 1/4 cups bleached cake flour, 1 1/2 teaspoons baking powder, 1 teaspoon fine sea salt, and 1/2 teaspoon ground nutmeg. Sifting blends these ingredients and introduces air for a lighter dough.

2-Second Step: Cream butter and sugar
In a stand mixer fitted with the paddle, or with a hand mixer, beat 2 tablespoons (29 grams) butter and 1/2 cup (100 grams) sugar until the mixture looks sandy and slightly pale. This step incorporates air and gives the dough a light texture. Add 2 large egg yolks and beat until the mixture is light and thick. Scrape the bowl as needed.

3-Third Step: Combine dry ingredients and sour cream
Add the dry ingredient mixture to the butter mixture in three additions, alternating with 1/2 cup (113 grams) sour cream. Start and end with the dry ingredients so the dough stays balanced. Mix on low speed just until smooth and slightly sticky. If the dough is too sticky to handle, add bleached cake flour 1 tablespoon at a time until it comes together; avoid adding too much or the donuts will be dense.

4-Fourth Step: Chill the dough
Cover the dough and chill it for 1 hour until it firms. Chilling keeps the dough slightly cold, which helps the donuts hold shape during frying. If the dough becomes too soft while rolling, refrigerate briefly until it firms up again.

5-Fifth Step: Roll and cut
On a lightly floured surface, roll the dough to 1/2 inch thickness. Cut out about 12 donuts and the corresponding holes using your preferred donut cutter or two round cutters. Gather scraps and gently reroll, keeping handling to a minimum so the donuts stay tender.

6-Sixth Step: Heat the oil
In a heavy, deep pot, heat 2 inches of canola oil to 325°F. Use a deep-fry thermometer to keep a steady temperature. Maintaining oil at 325°F is key: too hot and the outside burns before the inside cooks; too cool and the donuts soak up oil.

7-Seventh Step: Fry the donuts
* Fry donuts a few at a time so they have room to puff. Avoid overcrowding, which drops the oil temperature.
* Cook for about 2 minutes per side until golden but not burnt. Use a slotted spoon or spider to flip them gently.
* Drain excess oil on paper bags or a wire rack set over a sheet pan so the bottoms do not become soggy.

8-Eighth Step: Make the glaze
While the donuts cool slightly, whisk together the glaze: 3 1/2 cups (350 grams) sifted powdered sugar, 1 1/2 teaspoons corn syrup, 1/4 teaspoon fine sea salt, 1/2 teaspoon vanilla extract, and 1/3 cup hot water. Whisk until completely smooth. The hot water helps dissolve the sugar and yields a shiny glaze.

9-Final Step: Glaze and serve
Dip each warm donut into the glaze and place it on a wire rack set over a sheet pan to catch drips. Let the glaze set for 20 minutes before serving so it forms a thin, crisp shell. The donuts are best the day they are made, served warm with coffee.