Combine the eggs, flour, onion, salt, and pepper, stirring to blend. Using your hands, squeeze out as much liquid as you can from the potatoes. Add the potatoes to the egg mixture, mixing well.
In a large, heavy skillet, heat some of the oil over medium-high heat. Spoon the batter by quarter-cupfuls onto the hot skillet, flattening them with the back of the spoon. Fry until the bottom of the pancakes are nicely browned - between 3 and 5 minutes; flip the pancakes and cook for about 3 minutes longer. Repeat for the remaining pancakes, adding oil to the skillet as needed.
Drain on paper towels and serve immediately.
Grated potatoes make these pancakes fresh and crisp. I sometimes make them with leftover mashed. You can serve them for breakfast with homemade applesauce and sour cream, with an egg (soft yolk of course) or as a side for dinner.