Step 1

In a small bowl, sprinkle the yeast over the lukewarm milk. Stir briefly and allow to sit at room temperature until frothy, about 10 minutes.

Step 2

In the bowl of a stand mixer fitted with a dough hook or a large bowl, combine the flour, sugar, lemon zest, and salt.

Step 3

Mix in the milk and frothy yeast mixture, egg, egg yolk, and butter until a soft dough forms.

Step 4

Knead on a lightly floured surface just until elastic and smooth. Place in a large bowl, cover, and allow to rest at room temperature until doubled, 1-2 hours.

Step 5

On a lightly floured surface, divide the dough into 10 equal pieces (or 8 pieces for larger doughnuts).

Step 6

Roll each piece into a smooth ball, then flatten into a disc about 1/2 inch (1.25 centimeters) thick.

Step 7

Cover the discs with a towel and allow to rest at room temperature until puffed, about 30 minutes.

Step 8

Pour 2 inches (5 centimeters) of vegetable oil (or use lard) in a large saucepan and heat to 340˚F (170˚C), no higher.

Step 9

Line a baking sheet with paper towels and set aside.

Step 10

Once the oil is heated, gently stretch one of the puffed discs of dough to make a thin and almost translucent center at least 2 1/2 inches (6 centimeters) wide with a thicker at least 1 1/2 inch (4 centimeter) pillowy edge.

Step 11

Carefully place the stretched dough in the heated oil and fry until golden, 1-2 minutes. The thin center should puff up.

Step 12

Carefully flip the dough over to fry on the other side until golden.

Step 13

Transfer to the towel lined baking sheet and repeat with the remaining discs of dough, stretching right before you put them in the oil.

Step 14

These Schmalznudeln are best warm sprinkling with a dusting of powdered sugar.