Line a baking sheet with paper towels. Put a dish towel in a large colander and set over a large bowl.
Grate the potatoes on the large holes of a box grater and transfer to the towel. Grate the onion and add to the potatoes. Sprinkle with a pinch of salt and pepper. Firmly squeeze the mixture in the towel to extract as much liquid as possible; blot dry on paper towels if especially wet. Transfer the mixture to a large bowl. Add the kale, chives and dill and toss to combine. Add the flour and egg and stir until thoroughly combined.
Working with 1/4 cup of the mixture at a time, form tightly packed pancakes about 2 inches wide.
Heat 1/4-inch of oil in a large nonstick skillet over medium heat until shimmering. Working in batches, fry the pancakes until golden brown and crisp, 4 to 5 minutes per side. Remove to the prepared baking sheet and sprinkle with salt as you remove from the oil. Serve with sour cream and applesauce.