Stir together 1 T. of hot water and the soy sauce, mirin, worcestershire sauce, ketchup and mustard. Set aside.
Prep the pork:.
Place the pork cutlets between 2 sheets of waxed paper or plastic wrap and pound them with a meat pounder until about 1/4 inch thick. In a shallow bowl, lightly beat the egg. Spread the flour and panko on 2 separate plates. Season the flour with the salt and pepper. Also, season the pork cutlets with salt on both sides. Then dip the pork first into the flour, then the egg and last the panko (coating both sides). Press the panko into the pork so it stays put.
Panfry the pork:.
Heat a large nonstick skillet over medium-high heat until just hot and then add the oil. Add the cutlets and fry, turning once, until golden brown on both sides and just opaque at the center (you don't want to overcook pork) - this should take approximately 5 minutes on each side.
Tranfer the cutlets to paper towel to drain briefly, then cut across the grain into strips 1/2 inch thick.