To make these donuts, you need:-Bread flour-Instant yeast-Large egg-Warm milk-White granulated sugar-Unsalted butter-SaltFor the lemon curd:-Whole milk-Lemon-Large egg-Egg yolks-White granulated sugar-Cornstarch-Unsalted butter-Salt
First, whisk the warm milk to the egg and then add the yeast, stirring until dissolved. Then, add the salt, flour, and sugar to the mix. Stir until combined and then knead with your hands for 3 minutes.
Next, work the butter in with your hands before kneading for 2 or 3 minutes on a floured surface. Then, put the dough ball in an oiled bowl and cover with plastic wrap. Set in a warm space and let it rise for 3 hours.
To make the lemon curd, add the lemon peel and milk to a heavy saucepan over medium heat. When it steams, remove from the heat. Do not let it boil. Let it sit for 10 minutes for the milk to absorb the lemon flavor.
While you wait, whisk the sugar and eggs in a large bowl. Then, sift the salt and cornstarch together before adding them to the mixture. Whisk on medium high for about five minutes until it is pale yellow.
Now, remove lemon peel and pour the hot milk slowly into the egg mixture to tamper. Whisk constantly while adding. Then, boil over medium heat for 5 minutes. Remove from heat and add butter. Stir well.
Pour the mixture into a bowl and cover it with plastic. Let the plastic touch the surface so it does not produce a film. Let it cool for 20 minutes at room temperature before chilling in the fridge.
Then, punch down the dough and place it on a floured surface. Fold it a few times before cutting it into 8 pieces. Shape these pieces into balls and let them rise for 30 to 40 minutes on a pan covered in parchment.
After, fill a pan with 2 inches of oil and heat on medium low until it is 350 degrees F. Then, using a measuring cup, pour 1/4 to 1/3 cup of batter onto the pan. Cook until there are bubbles on one side and then flip and cook until golden.
After cooling completely on a wire rack, poke a hole in one side with a long stick like a chopstick. Then, coat both sides in sugar. Spoon the lemon curd into a piping bag and fill the donuts until there is just a little dot of yellow.