Peel your potatoes and quarter them. Boil for 15 minutes until fork tender. Strain in a colander and place them into a mixing bowl.
Meanwhile, fry your diced onions in 1 tbsp of oil until soft and translucent. Place into the mixing bowl.
Season your potatoes and onions with salt, garlic powder and black pepper.
Mash the potatoes and onions together and mix well. Then divide the potato batter into 8 equal portions. Roll them into oval shaped balls and place them in the fridge for 15 minutes (do not skip this step or you will have a difficult time coating them).
Meanwhile, in one bowl add corn starch. Then in the second bowl, whisk two eggs. Lastly in the third bowl, add your panko breadcrumbs.
Coat each ball in first cornstarch until evenly coated. Then coat in the egg and lastly cover with panko breadcrumbs.
Heat your 2 cups of oil over medium heat. To test if it's ready, place a wooden chopstick and look for bubbles. If you spot bubbles, it's time to deep fry.
Deep fry for 1.5 minutes on each side until golden crispy brown. Enjoy with homemade katsu sauce (recipe below).