Grate the potatoes with a box grater and add shreds to a large bowl of cold water to prevent oxidation.
In a separate bowl, combine flour, eggs, salt and pepper.
Remove potato shreds from water one handful at a time and squeeze out excess liquid, then add to the bowl with the flour mixture. Repeat this process until all of the potato shreds have been removed from the soaking water and squeezed of excess liquid.
Add grated onion to the bowl and mix all of the ingredients together to evenly coat.
Set a skillet over medium heat on the stovetop and add enough oil to coat the bottom of the skillet. Add approximately 1/2 cup of the pancake mixture to the skillet (or whatever size you prefer) and press flat into a disk. Fry for 3 minutes, or until golden brown, flip and fry for an additional 3 minutes.
Work in batches until all pancakes have been made, adding additional oil as needed. Keep potato pancakes warm in a 250 degree oven until ready to serve.