01 -
Combine warm milk, 1 teaspoon of sugar, and yeast in a bowl. Let stand for 10 minutes until foamy.
02 -
In a large bowl, mix flour, remaining sugar, salt, eggs, and lemon zest if using. Add the yeast mixture and softened butter. Knead by hand or with a mixer until the dough is smooth and elastic, about 10 minutes by hand or 5 minutes with a mixer.
03 -
Cover the dough and let it rise in a warm place for 1 hour or until doubled in volume.
04 -
Roll out the dough to a thickness of 1.5 cm. Use a round cutter (7–8 cm diameter) to cut out circles. Place on a floured surface, cover with a towel, and allow to rest for another 30 minutes until puffy.
05 -
Heat oil in a deep pan to 170–180°C. Fry 2–3 doughnuts at a time for 2–3 minutes per side until golden brown. Remove with a slotted spoon and drain on paper towels.
06 -
Once the doughnuts have cooled slightly, use a piping bag with a long nozzle to inject jam into the center of each. Generously dust with powdered sugar before serving.