Using a box grater or a food processor, grate the potatoes and onion together. If you are using a food processor, use the side of your hand to create a dam and pour off any water at the bottom of the food processor bowl.
Place a colander inside a large bowl. Place the onion and potato mixture in the colander and press the mixture to release additional water from the potatoes and onion. Place a damp paper towel on top of the mixture and cover the paper towel with a clean dish towel. Place in the refrigerator for one hour.
After one hour, remove the colander from the bowl and set it aside. **Very important** In the bottom of the draining bowl, there will be water. Carefully pour out the brown water, but leave the starch that collected, at the bottom of the bowl, this will help to bind the potato pancakes.
To the potato starch, add the beaten eggs, chopped scallions, and salt. Add the reserved potato and onion mixture and sprinkle with the panko. Toss to combine. The mixture will be very wet.
In a deep skillet, add enough vegetable oil to come up about ½” inside the skillet. Heat oil to temperature, or oil shimmers. Tip: Using the handle base of a wooden spoon, place in oil, when bubbles form around the handle base, the oil is at temperature.
Use your hand to scoop up about 1/3 cup of mixture and press firmly to form a pancake. Gently lay in the oil. Work in batches, making sure you have enough room for flipping.
Fry the latkes over medium-high heat, turning once until perfectly golden and crisp. Ours took about 4 minutes per side.
Transfer the latkes to baking grate and immediately season with salt. Repeat until you have used all the mixture.
Serve with applesauce, sour cream with chives, or smoked salmon.
If making ahead, heat oven to 350°, place latkes on a baking sheet, and bake for 8-10 minutes or until heated through and deliciously crisp.