Fill a heavy-bottomed pot with 1 ½ inches of Vegetable oil and preheat to 375 degrees F (190 C).
Vegetable oil
To make the Katsu Sauce, add the ¼ cup sake, 1 teaspoon black pepper, 1 teaspoon onion powder, and ¼ teaspoon garlic powder to a small saucepan and bring to a boil. Continue to boil until the bubbles get big and shiny.
¼ cup sake, 1 teaspoon black pepper, 1 teaspoon onion powder, ¼ teaspoon garlic powder
Add the ¼ cup Worcestershire sauce, 3 tablespoon ketchup, 2 tablespoon honey, 1 tablespoon whole grain mustard, and 1 tablespoon oyster sauce and let the mixture come to a boil again. Remove the sauce from the heat and let it cool.
¼ cup Worcestershire sauce, 3 tablespoon ketchup, 2 tablespoon honey, 1 tablespoon whole grain mustard, 1 tablespoon oyster sauce
For the Wagyu Katsu, beat the 1 large egg in a bowl. Add 50 grams panko to a shallow dish.
1 large egg, 50 grams panko
Sprinkle both sides of the 400 grams A5 Grade Wagyu Sirloin with the ¼ teaspoon coarse sea salt and ¼ teaspoon black pepper.
400 grams A5 Grade Wagyu Sirloin, ¼ teaspoon coarse sea salt, ¼ teaspoon black pepper
Sprinkle the steaks with the 2 tablespoons all-purpose flour and dust coat every surface of the meat with a thin, even layer. Pat the meat to dust off any excess flour.
2 tablespoons all-purpose flour
Dip the beef in the beaten egg, coating every surface.
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.
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).
Transfer the fried Wagyu Katsu to a wire rack and drizzle with a generous amount of sauce. Repeat with the second cutlet.
To assemble the sandwich, place a whole Wagyu Katsu between two slices of toasted sandwich bread.
4 slices Japanese sandwich bread
Trim off the crusts and slice the sandwich into halves or quarters.