1. The night before preparing the sourdough donut dough, create a sweet stiff starter.

   Alternatively, you can use 200 grams of 100% hydration active sourdough starter, but the donuts will be tangier. You will also need to omit the extra 55 grams of milk.

Sweet Stiff Starter

1. In a bowl, add the unfed starter, warm milk and sugar. Whisk until combined. Add the flour and mix until a shaggy dough. Then place the dough onto a clean work surface and knead until a smooth dough ball.

   My milk was 100 degrees F , don't use any hotter, otherwise that can kill your sourdough starter. If you use cooler milk, the sweet still starter will take longer to rise.
   20 grams unfed starter, 55 grams milk, 15 grams sugar, 110 grams bread flour
2. Place back into the bowl, cover with plastic wrap and leave to triple in size.

   In my kitchen was 70 degrees F, it took about 12 hours for the sweet stiff starter to have tripled in size. You know your starter is ready to use when it has tripled in size, has a domed top, has a pleasant sweet aroma and is full of webbing when torn open.

Tangzhong

1. Before mixing the dough, prepare the Tangzhong.
2. Add the milk and flour to a small saucepan or skillet and whisk until the flour has been incorporated. Bring to medium heat. Whisk continuously until a thick paste forms, about 4-5 minutes. Remove the saucepan from heat and allow the Tangzhong to cool before preparing the dough.

   Note: It’s important to cool the Tangzhong before adding it to the dough. To do this quickly, spread the thick paste over a large plate, cover it with plastic wrap and place it into the fridge. It should be cool enough within 5-10 minutes.
   160 grams milk, 35 grams bread flour

Donut Dough

1. In a bowl of a stand mixer fitted with the dough hook, add the bread flour, sugar and salt and give the dry ingredients a quick whisk. Then add the room temperature Tangzhong, room temperature egg and milk. Divide the stiff sweet starter into 15-20 pieces and add it to the mixing bowl. Mix on low/stir for about 2-3 minutes or until all of the ingredients are incorporated and a stiff, thick dough forms.

   You can also do this by hand. I would increase the kneading by 5 minutes or until the dough passes the windowpane test.
   300 grams bread flour, 66 grams sugar, 10 grams instant yeast, 6 grams salt, 1 egg, all the sweet stiff starter, all of the tangzhong, 55 grams milk, room temperature
2. While still mixing on low, add one tab of butter at a time letting it fully incorporate before adding more.
   70 grams unsalted butter, room temperature
3. Once all of the butter has been added, increase to medium speed (speed 2) and knead the dough for 10-15 minutes more or until the dough passes the windowpane test.
4. Signs that Your Dough Has Been Kneaded Enough:

   - It is no longer sticky.

   -Instead, the dough is smooth, elastic and tacky to the touch.

   -The dough passes the windowpane test. This means the dough no longer tears when spread out thin enough that light passes through.
5. Place the dough in a lightly greased straight-edge bowl straight-edge bowl, cover and leave to double in size

   Note: Enriched dough rises much better around 75–78°F, so if your kitchen is cool, use a proofing box or another warm spot to help the donuts become light and airy. I love using my Brod & Taylor Proofing Box for consistent results. This enriched dough took about 4-5 hours to double in size at 77 degrees F.
6. Pour the dough onto a lightly floured work surface and dust the top with more flour. With a floured rolling pin, roll the dough out to ½-¾ inch thick.
7. Using a donut cutter, cut out about 8-9 donuts. Knead the scrapes and wait about 30 minutes before rerolling and cutting out more donuts. You want to give the dough enough time to relax before rolling out again.

   Note: Try to cut as many donuts as you can the first time because I found the donuts cut from the re-kneaded dough tended to be a little more tough. Also, use a smaller ring to cut out as many donut holes with the remaining sourdough donut dough!
8. Place each donut and donut hole on its own square of parchment paper, then place on a rimmed baking sheet. Cover and leave to rise until doubled in size and puffy.

   I proofed my donuts in my oven at 77 degrees F using the proofing setting. This took about 1-2 hours or until they look super light, almost marshmallow-like and jiggle when shaken. Alternatively, you can cover the donuts in the fridge overnight and continue with the 2nd rise the following morning.

   Note: Since the dough will be cold from the fridge, the 2nd rise will take longer to complete, about 2-3 hours at 77 degrees F. Don't rush this step! Cold and underproofed dough will result in dense, bread-like donuts.
9. Just before the donuts have completed their 2nd rise, preheat 2 inches of oil to 360 degrees F in a heavy-bottom pot or 12-inch cast iron skillet. I love using this frying thermometer!
   neutral oil for frying
10. Once the donuts have completed their 2nd rise, carefully place 2-3 donuts (parchment paper included) in the hot oil at a time. Use kitchen tongs to remove the parchment paper after about 10 seconds. Continue to fry each donut for 2 ½ minutes total, flipping halfway through.
11. Using a slotted spoon, carefully remove the golden brown sourdough donuts and place them on a wire rack to drain. Continue to fry the remaining donuts.

    IMPORTANT: Make sure the oil temperature returns before frying the next batch.

Vanilla Glaze

1. In a medium bowl, whisk together the powdered sugar, hot water, vanilla extract and salt until smooth. Dip each side of the donut in the glaze, allowing any excess to drip off, then place back on the wire rack to dry.
   430 grams powdered sugar, 95 grams hot water, 6 grams vanilla paste or extract, pinch of salt
2. Wait about an hour until the donuts are fully set. Enjoy!