Thoroughly wring out the liquid in the grated potatoes by placing them in a colander and squeezing them with your hands or by placing them in a clean dish towel and wringing out the liquid.
Place the drained grated potatoes in a medium-sized bowl with the grated onion, eggs, flour and salt and use your hands to work it into a tacky mixture. Add a little more flour if needed. Do no let the mixture sit for long before using it, use it immediately.
Heat a few tablespoons of oil in a non-stick pan over medium-high heat and place 1/3 to 1/2 cup of the mixture (depending on size preference) in the hot pan and flatten into pancakes with the back of a spoon. Fry on both sides for 3-5 minutes until the Kartoffelpuffer are golden. Place them briefly on paper towels.
Serve immediately while hot with applesauce, fruit compote or powdered sugar. For a savory version serve with herbed yogurt, quark or creme fraiche or with meat and gravy as part of a meal.