Preheat the oven to 400°F. Lightly grease two large cookie sheets with rims. (Alternatively, pan-fry.)
Grate or shred the potatoes fine or medium-fine; no need to peel them first, though they should be washed.
Wrap the grated potatoes in a cotton dish towel and twist the towel closed at the top. Squeeze them to wring as much liquid as possible from them.
Shred or grate the onion finely.
Combine the drained potatoes, onion, egg, salt, and flour in a bowl, stirring till everything is thoroughly mixed.
Pour a thin layer of vegetable oil into each baking pan (or into skillet).
Drop the batter onto the sheets by the ¼- to ⅓-cupful, spacing them far enough apart. (If pan-frying, drop spoonfuls of the potato mixture in hot oil, pressing down to form patties.)
Bake for 20 to 25 minutes, or until the bottoms are golden brown. (In a pan, cook until golden brown on both sides.)
Remove the pans from the oven, turn the latkes over, and bake for an additional 10 minutes, until golden brown on the bottom.
Remove from the oven, and drain on paper towels. Serve immediately, with applesauce and sour cream, if desired.
