Prepare a sheet pan lined with paper towels and place it near the stove. In a large bowl, mix the eggs, flour, salt, and pepper until well combined.

Grate the potatoes and onion using the largest holes of a box grater, discarding any tough onion pieces. Place the grated mixture onto a clean dish towel or large cheesecloth and wring it out over the sink to remove as much liquid as possible.

Add the grated potatoes and onion to the bowl with the egg mixture. Combine everything gently but thoroughly using your hands or a wooden spoon.

Heat 1/3 cup canola oil in a large (12-inch) skillet over medium-high heat until it shimmers. Scoop 1/4 cup portions of the potato mixture into the skillet, using the bottom of the measuring cup to flatten them slightly. Fry in batches to prevent overcrowding. Cook until the pancakes are golden brown, about 2 to 3 minutes per side. If the pancakes brown too quickly or the oil starts to smoke, reduce the heat. Transfer cooked pancakes to the prepared sheet pan and lightly season with salt.

Continue with the remaining batter, adding more oil as needed and adjusting the heat as necessary. Discard any small pieces of leftover batter and drain any excess liquid from the bowl. Serve the pancakes hot with optional sour cream and chives.