Preheat oven to 400°F. Spread 3 Tbsp. oil on each of 2 large, rimmed baking sheets (see Tip). Line a third tray or platter with paper towels for placing pancakes once cooked.

Drain sauerkraut in a colander, then press firmly to release more liquid; let drain 10 minutes. Meanwhile, spread a clean kitchen towel on the counter. Using a box grater, coarsely grate potatoes and onion and spread out on the towel. Add a few layers of paper towels on top and press down firmly to dry. Roll up the towel, twist the ends tightly, and squeeze out any extra liquid over the sink. Transfer the potatoes and onion to a large mixing bowl and stir in the drained sauerkraut, egg, flour, salt and pepper.

Using a 1⁄4 cup measuring cup, scoop batter onto the oiled baking sheets, placing 8 or 9 pancakes per pan. Flatten the batter out so each is 3 to 4 inches wide and about 1/4-inch thick, especially in the center. (Ensure there is space between each one so they can brown properly in the oven.) Bake two pans at a time about 15 minutes until the pancake edges start to brown. Flip over and bake 10 to 15 more minutes until light brown in the center and edges are deep brown. Transfer cooked pancakes to the paper towel-lined tray and repeat with the remaining batter. Serve warm with applesauce, sour cream and chives.