In a large bowl, mix together the grated potatoes and onion. Squeeze out any excess moisture using a clean kitchen towel or paper towels.
Add the beaten egg, flour, salt, and black pepper to the bowl and mix well until all ingredients are combined.
Heat the vegetable oil in a large non-stick pan or skillet over medium heat.
Scoop about ¼ cup of the potato mixture into a circle mold or cookie cutter and onto a parchment lined cookie sheet, pressing down lightly with a spatula to flatten. Repeat with the whole mixture. Place onto the pan one by one.
Cook the pancakes for about 3-4 minutes per side, or until they are golden brown and crispy.
Remove the pancakes from the pan and pat off any excess oil.
Serve the pancakes hot with scallions and sour cream and enjoy!