For the Egg Salad:
2 large hard-boiled eggs, peeled and finely chopped
2 tablespoons, plus 1½ teaspoons, Kewpie mayonnaise
1 tablespoon Dijon mustard
3 cornichons, finely chopped
¼ teaspoon freshly ground black pepper
For the Katsu Sando:
2 boneless, ½-inch-thick pork chops
Kosher salt, to taste
2 tablespoons all-purpose flour
1 large egg
1 cup panko (Japanese bread crumbs)
Canola oil, for frying
2 tablespoons tonkatsu sauce, plus more to taste
4 slices white sandwich bread, crusts removed
1. Make the egg salad: In a medium bowl, stir together the eggs, Kewpie mayonnaise, Dijon mustard and cornichons. Season with the pepper and set aside. Makes 1 cup of egg salad and can be refrigerated up to 2 days in advance.
2. Make the katsu sando: Using a mallet, pound the pork chops between 2 pieces of plastic wrap to a ¼-inch thickness. Season the pork chops with salt and sprinkle with the flour.
3. In a shallow bowl, beat the egg. Place the panko in another shallow bowl. One cutlet at a time, dip the pork into the egg mixture, letting the excess drip back into bowl, then coat the cutlet in panko, shaking off any excess.
4. Pour enough oil into a large skillet until it reaches a depth of ¼ inch and place over medium-high heat. When the oil begins to ripple, add the pork cutlets and fry until golden brown and cooked through, 2 minutes per side. Transfer to a paper towel-lined plate to drain and season lightly with salt while still hot.
5. Squeeze the tonkatsu sauce onto one side of each slice of bread. Sandwich each pork cutlet in between two slices of bread and cut in half. Serve cut-side upright with the egg salad on the side.