To make the sandwich, place the chicken fillets between two pieces of plastic wrap and, using a heavy skillet or something else heavy and large, pound the fillets flat until about an inch thick.

Sprinkle generously with salt and pepper. Prepare three plates and place flour, egg and panko in them. Dredge the chicken breasts in the flour, then the egg, then the panko. For an extra nice crispy coating, pass the chicken breast through the egg and panko again creating a double layer.

Finely chop the cabbage. Toss the cabbage with two tablespoons of the mayo and season with salt and pepper.

Mix the ketchup, mustard, and Worcestershire sauce together to make a nice sauce.

Heat the oil to 180˚C/350˚F and fry the fillets until golden brown, drain on a rack or paper towel.

Spread the sandwich with mayo, place the crispy chicken on top, then a generous spoonful of white cabbage. Top with a generous spoon of red sauce and cover with the second slice of bread. Cut the crusts off the bread. Then, if all goes well, cut off some of the chicken to give you that special katsu sando look. Of course, you can also eat the rest, it would be a waste to throw it away.