How to Make it:
Preheat oven to 250F with rack in upper and lower thirds. Place cooling racks on top of large shallow baking pans.
Peel potatoes and coarsely grate into a bowl using large teardrop-shaped holes of a box grater or in a food processor fitted with medium shredding disk. Add lemon juice and toss to coat.
Coarsely grate onion into same bowl. Transfer mixture to a kitchen towel. Enclose mixture in towel and wring out as much liquid as possible. (Discard liquid)
Wipe bowl clean, then return potatoes and onion to bowl and stir in flour, eggs, salt, and pepper until just combined.
Heat oil in a large nonstick skillet over medium-high heat until hot but not smoking. Fill a 1/4-cup measure with latke mixture and carefully spoon it into skillet, then flatten lightly with a heatproof spatula.
Form 5 more latkes in skillet and fry until undersides are golden, 2 to 3 minutes. (If latkes brown too quickly, reduce heat.) Turn over and fry until golden on other side, about 3 minutes more. Transfer to paper towels to drain briefly, then transfer to a metal rack set on baking pan in oven to keep warm. Make more latkes in same manner. Serve with sour cream, applesauce, or whatever you like.
Make ahead tip: Latkes can be kept warm in the oven for up to 1 hour
Makes: 36 latkes