4Microwave for 1 minute, remove and whisk thoroughly, repeat this process 4-6 more times until the mixture is thick enough to coat the back of a spoon.
5Allow to cool and then place into the fridge until ready to use.
6Whisk together the flour, sugar, baking powder, baking soda, and salt.
7Whisk together the buttermilk, egg, greek yogurt, and vanilla until combined.
8Add the melted butter and whisk until fully incorporated.
9Add the dry ingredients to the wet, and fold with a spatula or wooden spoon until just combined (the dough will be sticky).
10Add the blueberries and very gently fold them in until evenly dispersed.
11Cover the bowl and place in the fridge to chill for at least 30 minutes.
12Fill a large, heavy-bottomed pot or Dutch oven with oil, filling ~2” in the pan.
13Heat on medium-high until it reaches 350F-370F.
14Line a wire cooling rack with a thick layer of paper towels.
15Use a small cookie scoop to scoop the dough and drop directly into the hot oil.
16Add 6-8 donut holes at a time, frying for 2-4 minutes, until golden. I tossed mine using a fork to continually flip them over during the frying process.
17Use a slotted spoon to carefully remove and transfer to the rack with paper towels.
18Repeat with the remaining dough.
19Make the glaze by whisking together all of the ingredients in a medium bowl, until smooth.
20Dunk each donut hole into the glaze and toss to coat.
21Set on a cooling rack until the glaze sets.
22Transfer the lemon curd to a piping bag fitted with a long, filling attachment.
23Gently insert the pastry filling tip into the donut holes and squeeze some lemon curd inside.