Step 1

Line 2 rimmed baking sheets with paper towels.

Step 2

Fill a large stockpot or saucepan with cold water. Add 1 pound russet potatoes and 1/4 cup of the kosher salt, and bring to a boil over medium-high heat. Boil until you can poke the potato with a fork or a paring knife and it pierces easily all the way to the center, about 30 minutes. Meanwhile, dice 1 small yellow onion (about 1 cup). Thinly slice 4 medium scallions (about 1 cup). Dice 1 small carrot (about 1/2 cup).

Step 3

Drain the potatoes and let cool while you cook the meat and vegetables.

Step 4

Heat 1 tablespoon of the vegetable oil in a large frying pan over medium-high heat until shimmering. Add 8 ounces ground pork and cook, breaking up into small pea-sized crumbles, until browned and cooked through, about 5 minutes. Season with 1 teaspoon of the kosher salt and 1/8 teaspoon ground white pepper. Add the onion, scallions, carrot, and 1/2 cup fresh or frozen peas. Cook until onion is translucent and the carrots are just tender, about 3 minutes. Remove the pan from the heat and let cool to room temperature, about 15 minutes.

Step 5

Once the potatoes are cool enough to handle, peel and discard the skins. Return the peeled potatoes to the pot and mash with a potato masher until there are no more large lumps and the mixture is just smooth.

Step 6

Add meat and vegetable mixture and mix until well combined. Taste and season with more kosher salt and white pepper as needed. Scoop the mixture into 1/4 cup portions (about 13). Form each into an egg shape patties and place on a baking sheet. Refrigerate until firm, 30 minutes to 1 hour.

Step 7

Place 1 cup panko breadcrumbs in a wide, shallow bowl and season with 1/4 teaspoon of the kosher salt. Crack 2 large eggs into second shallow bowl, whisk lightly, and season with the remaining 1/4 teaspoon kosher salt. Working one at a time, dredge a korokke in the eggs until completely coated, then place in the panko and turn until completely coated. Return to the baking sheet.

Step 8

Fill a medium saucepan with enough vegetable oil to come at least 3 inches up the side (about 2 cups). Heat over medium-high heat until 340 to 360ºF. Meanwhile, line a second baking sheet with paper towels.

Step 9

Fry the korokke 3 at a time: Add to the hot oil and fry until deep golden-brown all over, about 3 minutes per side. Transfer to the baking sheet. Serve warm or at room temperature with tonkatsu sauce.