Add warm water, sugar and yeast to the bowl of stand mixer, stir to combine and allow to sit for 15 minutes, or until yeast is activated and foamy. Add milk, egg, butter, salt, and orange zest and stir to combine. Using a dough hook, and the stand mixer on low speed, gradually add the flour. Once all the flour has been added, increase the speed to medium and knead for approximately 5 minutes, or until a smooth dough has formed.
Spray a large mixing bowl with cooking spray, and add the dough. Cover the bowl with plastic wrap and place in a warm place. Allow the dough to rise for 2 hours, or until dough has doubled in size.
Fill a large pot or Dutch oven just under half way with vegetable oil, and heat to 335ºF. Turn the dough on to a lightly floured work surface and cut in half. Roll half of the dough into a large rectangle. Roughly ½ cm thick. Cut the rectangle into 5 cm squares, and place them on a sheet pan lightly dusted with flour. Repeat with the remaining dough.
Working in batches, fry the dough for 1-2 minutes per side, or until puffed and golden, remove to a sheet pan lined with paper towel and allow to stand for 1 minute. Generously dust with icing sugar. Serve immediately.
