Using the finest holes of a box grater, grate the potatoes into a large bowl lined with cheesecloth. Wrap the cheesecloth around the grated potatoes, then squeeze to wring out as much liquid as possible. Discard the liquid, then return the grated and drained potatoes to the bowl.

Using the same holes of the box grater, grate the onion. Add the onion to the bowl with the potatoes and mix well.

Using a wooden spoon, stir the egg yolks and matzoh meal into the bowl with the potatoes and onion. If needed, add a bit more matzoh meal to thicken the mixture.

In a cast iron skillet, heat the oil over medium heat. Once the oil is hot, working in batches, gently drop spoonfuls of the potato mixture into the skillet, then flatten into pancakes with a spatula. Cook, flipping halfway through, until golden brown on the outside and cooked through inside. Keep a careful eye on the heat, making sure the oil is sizzling but not smoking, and reduce the heat if needed to avoid making latkes with raw insides and burned outsides. Be patient—the latkes will crisp up in time!

Transfer the cooked latkes to a paper towel–lined plate to drain. Serve with applesauce or smoked salmon and eggs.