Jelly Donuts (Sufganiyot)

Directions

1. In the bowl of a mixer, combine the flour and yeast. Add the milk, butter, sugar, egg, egg yolk, salt, lemon zest, and vanilla. Mix on medium speed with the dough hook attachment for 8 to 12 minutes. The dough should have very strong gluten development and be tight but smooth. It will still be slightly sticky, but should not feel wet.
2. Transfer the dough to a large, lightly-oiled bowl. Cover and set aside to ferment until doubled in size, about 1 hour.
3. Line a baking sheet with parchment paper. Divide the dough into 10 pieces, and shape each piece into a tight round and press lightly with the palm of your hand to flatten slightly. Transfer, seam side down, to the baking sheet.
4. Cover loosely with a clean kitchen towel, and set aside to proof until the dough springs back slowly to the touch but does not collapse, 45 to 60 minutes.
5. Heat the oil in a heavy-bottomed pot over medium heat until it reaches 350°F.
6. Meanwhile, line 2 baking sheets or cooling racks with paper towels. Place the jam in a piping bag with a #2 tip, and place the coating sugar in a shallow bowl.
7. Carefully transfer the proofed donuts, a few at a time, seam side up, to the hot oil, adjusting the heat as needed to maintain the oil temperature. Use a spider or other heat-safe tool to keep the dough submerged, until golden brown on the first side, 1 minute. Flip and fry, not submerged, another 1 1/2 minutes. Turn once more and fry until the top is deep golden brown, 20 to 30 seconds. Lift the donuts from the hot oil with a spider or tongs, allowing the oil to drain away over the fryer. Drain on paper towels just until cool enough to handle.
8. Use the piping tip to make a small hole in the side of the donut and inject jam into the donut. Dip both sides of each one in granulated sugar and place them on a rack to cool. Chef’s Note: If you do not have a piping tip, use a small paring knife to cut a hole in the donut. Use a piping bag or zip-top bag with a corner cut off to pipe jelly into the hole.