In a large saucepan over medium high heat, add the finely chopped strawberries with ¼ cup sugar. Simmer until bubbly and juicy, about 4-5 minutes. Remove from heat to cool.

In a large bowl, combine the flour, salt, and remaining ¼ cup sugar. Mix well.

Add the active sourdough, milk, ⅓ cup strawberry syrup, beaten egg, vanilla, and finely chopped strawberries. Mix until no flour clumps are left. If the batter seems too sticky, add up to ½ cup more flour. Reserve any remaining strawberry syrup for the glaze.

Cover and let rest 30 minutes.

Lift one corner of the bowl, stretching as high as it’ll go without breaking the dough, and fold over the center. Rotate the bowl 90 degrees and repeat, imagining if the bowl was divided into 4 corners. Repeat a total of 8 times. Cover and rest 30 minutes.

Repeat the lift and fold process once more. Cover and allow to bulk ferment in a warm environment for 8-10 hours, ideally overnight.

After the bulk fermentation, roll out on a heavily floured surface to ½" thick. Use a large cookie cutter, about 3" wide, to make the donuts. Place on a large piece of parchment paper at least 2-3" apart from one another. Use a smaller cookie cutter to cut the centers, also placing on the parchment for donut holes.

Cover lightly with a tea towel or plastic wrap to rest for 2 hours, until doubled in size.

Heat up the frying oil to 350F.

Use kitchen scissors to cut the parchment paper around each individual donut for easy placement into the frying oil. After 10 seconds, use tongs to help remove the parchment. Fry in small batches for 30 seconds to 1 minute on each side, until deeply golden and crisp on the edges.

Use a slotted spoon to remove to a wire rack lined with parchment paper to drain excess oils.

To Make the Strawberry Glaze: Combine the powdered sugar and ¼ cup remaining strawberry syrup, adding water or heavy cream as needed, to make a thick glaze.

Dip each donut into the strawberry glaze, then let rest for at least 10 minutes to help the glaze set before enjoying!