Grate the peeled sweet potatoes and onion using the coarse side of a box grater or a food processor fitted with a grating attachment. Place the grated sweet potatoes and onions in a clean kitchen towel, a few paper towels or cheesecloth. Squeeze out as much liquid as possible.
In a large mixing bowl, combine the squeezed sweet potato and onion mixture, beaten eggs, flour, kosher salt, and black pepper. Mix well until all the ingredients are thoroughly combined.
In a large, heavy-bottomed skillet, heat about 1/4 inch of vegetable oil over medium-high heat until it shimmers. You can also use a deep fryer if you prefer. You want it to reach and stay at 350F-375F before adding so they don't soak the oil in and get crispy.
Using a spoon or your hands, shape the sweet potato mixture into 2-3 inch patties, squeezing out any excess liquid.
Carefully place the patties into the hot oil, being cautious not to overcrowd the pan. You may need to work in batches. Fry the latkes for about 3-4 minutes per side, or until they are golden brown and crispy. Use a slotted spatula to flip them.
Remove the latkes from the oil and place them on a paper towel-lined plate to drain any excess oil. Serve the sweet potato latkes immediately while they are hot and crispy. If desired, serve with applesauce or sour cream on the side.