Berliner Donuts

Instructions

1. Prepare the yeast mixture
   In a small bowl, combine the warm milk, 1 tablespoon of sugar, and the yeast. Stir gently and let it sit for about 10 minutes until foamy and activated.
2. Mix the dough
   In a large mixing bowl or stand mixer, combine the flour, remaining sugar, salt, and lemon zest. Make a well in the center and add the yeast mixture, eggs, softened butter, vanilla extract, and rum (if using). Mix until a soft dough forms, then knead for 8-10 minutes until smooth and elastic.
3. First rise
   Place the dough in a lightly oiled bowl, cover with a clean kitchen towel or plastic wrap, and let it rise in a warm place for about 1 hour, or until doubled in size.
4. Shape the donuts
   Punch down the dough and turn it out onto a lightly floured surface. Roll the dough to about 1/2 inch thickness. Using a 3-inch round cutter, cut out circles. Place the circles on parchment-lined baking sheets, cover, and let them rise for another 30-45 minutes until puffy.
5. Heat the oil
   In a heavy-bottomed pot or deep fryer, heat the oil to 350°F (175°C). Use a thermometer to monitor the temperature, as it's crucial for proper cooking.
6. Fry the Berliners
   Carefully lower 2-3 donuts into the hot oil. Fry for about 90 seconds on each side until golden brown. Use a slotted spoon to remove them and place on paper towels to drain excess oil.
7. Fill with jam
   Once the donuts have cooled slightly but are still warm, use a piping bag with a long filling tip to inject about 1-2 tablespoons of jam into the side of each donut. Alternatively, you can cut a small slit in the side of each donut and spoon the jam inside.
8. Finish and serve
   Dust the filled Berliners generously with powdered sugar. Serve them fresh, preferably the same day they're made, though they'll keep for 1-2 days in an airtight container.