In a food processor or on the large holes of a box grater, coarsely shred the potato and onion. Transfer to a lint-free towel and wring out as much liquid as possible. Let stand for 2 minutes, then wring it out again.

Transfer wrung-out potato and onion shreds to a large bowl, and add potato starch, salt, and pepper and toss to coat strands. Add egg and mix until evenly coated.

Place your empty skillet over medium heat and heat for 2 minutes. Increase the heat to medium-high and pour ¼-inch of oil into the pan. Let it heat a full minute before adding your first latke.

Form your latkes in packed tablespoons or twirl some strands around a fork. Transfer to the heated oil and carefully lower in the pan. Repeat with more pancakes, spacing them out. Flatten them slightly if you prefer a thinner latke.

Cook the latkes until the undersides are browned, about 1 ½ minutes; then carefully flip and cook until equally colored on the second side, about 1 minute.

Transfer latkes to paper towels to blot excess oil. Repeat with the remaining potato mixture.

To keep latkes warm, heat oven to 175°F and keep a large baking sheet inside. Cover it with foil for easier cleanup. As you fry the latkes, drain them briefly on towels and transfer to this tray in the oven.

Latkes can be kept in the fridge for a day or two, or in the freezer for up to two weeks. Reheat them on a baking sheet at 375°F until they're crisp all over again.