Step 1

Fill a heavy-bottomed pot with 1 1/2 inches of oil and preheat to 375 degrees F (190 C).

Step 2

To make the Katsu Sauce, add the sake, black pepper, onion powder, and garlic powder to a small saucepan and bring to a boil. Continue to boil until the bubbles get big and shiny.

Step 3

Add the Worcestershire sauce, ketchup, honey, mustard, and oyster sauce and let the mixture come to a boil again. Remove the sauce from the heat and let it cool.

Step 4

For the Wagyu Katsu, sprinkle both sides of the steaks with the salt and black pepper.

Step 5

Sprinkle the steaks with the flour and dust coat every surface of the meat with a thin, even layer. Pat the meat to dust off any excess flour.

Step 6

Dip the beef in the beaten egg, coating every surface.

Step 7

Place the egg and flour-coated meat on a bed of panko and it with panko, patting gently to help the panko adhere to the steak.

Step 8

Add the steak to the preheated oil and fry for 30 seconds on one side. Flip the cutlet over and fry until it's golden brown (about another 30 seconds).

Step 9

Transfer the fried Wagyu Katsu to a wire rack and drizzle with a generous amount of sauce. Repeat with the second cutlet.

Step 10

To assemble the sandwich, place a whole Wagyu Katsu between two slices of toasted sandwich bread.

Step 11

Trim off the crusts and slice the sandwich into halves or quarters.