Berliner - German Jam Doughnuts

Preparing the Dough

1. In a mixing bowl, combine the lukewarm milk and dry yeast. Let it sit for a few minutes until it becomes frothy.
2. Transfer the yeast mixture to a stand mixer bowl fitted with a dough hook attachment.
3. Add the sugar, vanilla bean paste, flour, salt, and vinegar to the yeast mixture in the stand mixer bowl. 
4. Mix on low speed until a dough forms and then add the egg yolks.
5. Once the dough has come together, add the softened butter in very small portions piece by piece, and let it incorporate into the dough before adding more. 
6. Let the mixer knead the dough for 8 to 10 minutes until the dough is smooth, elastic, and no more sticky. 

Proofing and Shaping the Doughnuts

1. Place the dough in a lightly oiled bowl, covet it with cling film or a clean kitchen towel.
2. Let the dough rise for 1 hour, or until it doubles the size in a warm place.
3. Once the dough has risen, divide it into 12 equal pieces, each weighing approximately 70 grams.
4. Roll each dough portion into a ball and flatten it slightly to form a doughnut shape.
5. Place them on a baking paper-lined tray, lightly sprinkle with flour, and cover them with a clean kitchen towel or cling film.
6. Let them rise for another hour until they have doubled in size.
7. Remove the cover and allow them to rise for an additional 30 minutes, allowing a slight crust to form.

Frying and Filling the Doughnuts

1. Heat the oil in a deep frying pan or pot to 165°C (330°F).
2. Carefully place the risen doughnuts into the hot oil and fry for about a minute on each side or until they turn golden brown and puffy.
3. Do not overfill the pan; do it in 2 or 3 batches, depending on the size of your frying pan.
4. Remove the Berliners from the oil using a slotted spoon and place them on a paper towel-lined wire rack to drain excess oil.
5. If you want your Berliners sweeter, allow them to cool down for 10 minutes, or until they are easier to handle, and then roll them in caster sugar.
6. Allow them to cool down to room temperature, and then, using a jam filler or a thin-nozzled piping bag, fill each Berliner with your choice of jam.
7. Dust them with icing sugar and serve while still warm and fresh.