Peel and grate the potatoes into a bowl and add cold water to cover. Let stand 15 minutes to extract the starch from the potatoes. Using a slotted spoon, remove the potatoes, drain, and let the water they were soaking in sit for a few minutes.
Carefully pour off the water, leaving the sediment in the bowl. This sediment is the starch from the potatoes and will help the pancakes to bind.
Place the potatoes in a clean towel and gently squeeze out any remaining water.
Add the onions, cilantro, flour, wasabi, garlic, eggs, and salt to the bowl with the potato starch and mix to combine. Add the potatoes and stir to mix.
Heat a large, heavy skillet over medium heat, pour in the oil to a depth of 1/4 inch, and when it’s hot, spoon 1/4 to 1/3 cup of the potato mixture into the oil. Flatten the pancakes to about half-inch thick.
Fry the pancake for 6 minutes, or until browned, turn over, and fry the other side until browned.
Remove and drain the pancakes on a paper towel before serving.