3 cups apple cider
4 cups all purpose flour, plus extra for dusting your kneading surface
1 cup potato starch (no substitutions)
2 cups sugar
1 tablespoon plus 2 teaspoons baking powder
1/2 teaspoon pumpkin pie spice
1/2 cup evaporated milk
3/4 teaspoon kosher salt
vegetable oil for frying
Pour the apple cider into a saucepan and bring to a boil. Continue cooking on medium heat until its volume is reduced from three cups to one cup (about 10 to 15 minutes). Once reduced, pour the cider into a small mixing bowl or liquid measuring cup and place it in the refrigerator to cool.
In a large bowl, stir together the flour, potato starch, sugar, baking powder, and spice, using a heavy spoon or spatula. Make a well in the center of the mixture.
Whisk the eggs, evaporated milk, salt, and reduced apple cider together until well combined, then pour into the well in the center of the dry ingredients. Use your spoon or spatula to gradually mix them together just until they are fully incorporated. (Do not overmix and do not use an electric mixer.)
Generously flour a clean counter or wooden board, as well as your hands. Pour the sticky doughnut batter out of the bowl and gently knead for about one minute until it forms a cohesive dough. Pat it out to a thickness of about 1/2″, then cover it with plastic wrap and allow to sit at room temperature for 30 minutes, during which time the dough will suck up the excess moisture and stop being sticky. What you’ll have is a nice, soft bouncy dough that you can easily cut through without issue. (If, for some reason, it still feels a bit sticky when you touch it, dust your hands with a bit of potato starch and give the top of the dough a light pat.)
Fill a Dutch oven or your largest pot with at least 4 inches of frying oil. Clip a fry/candy thermometer to the side of the pot, making sure that the bulb doesn’t touch the bottom. Turn the heat on thigh, bring up to a temperature of 360 degrees Fahrenheit, then lower heat to medium, adjusting as necessary to maintain temperature.
Use a doughnut cutter or round biscuit cutter to punch out doughnuts from the dough. If using a biscuit cutter, stick your finger through the center of the doughnut to make a hole, then twirl it around a bit to stretch it out. The doughnuts don’t need to look perfect.
Drop two or three doughnuts into the oil at a time. (If you put in too many at the same time, the oil temperature drops and causes the doughnuts to absorb too much oil.) They will sink to the bottom at first, and then, as the baking powder is activated, they will puff up and rise to the top. Fry for about two minutes, peeking at the undersides with a slotted spoon or chopstick, and flipping over when golden brown. Continue to fry for another minute or two, then remove from the oil and place on a wire rack over a baking sheet to drain and cool. Repeat with the remaining doughnuts. You can reroll the scraps to punch out more doughnuts, or you can hand shape them into tiny balls to make doughnut “holes.”
If you’d like to sugar your doughnuts, put some granulated or superfine sugar into a cake pan, and add your doughnuts while they are still hot and just shake them around. Use a spoon to make sure both sides are covered in sugar, then move to the rack to cool completely. If you’d like to dust with powdered sugar, wait until the doughnuts have cooled to room temperature, then dust right before serving.