Taiki Nakajima opened his food truck after a trip back to his hometown of Tokyo, where he found simple, addictive sandwiches in nearly every convenience store. His favorite was a pork katsu sando, and he has become known for his version: fried panko-crusted cutlets sandwiched between soft white bread with cabbage, tonkatsu sauce and Dijon mustard.
Using the flat side of a meat mallet or the bottom of a heavy skillet, pound each pork chop until 1/4 inch thick and about 3 1/2 by 6 inches. Season both sides with salt and pepper. Put the flour, egg and panko in 3 separate shallow dishes. Dredge the pork in the flour, shaking off the excess, then dip in the egg and dredge in the panko. Set on a plate.
Fill a large Dutch oven or other pot with 2 inches of vegetable oil and heat over medium-high heat until it registers 350˚ F on a deep-fry thermometer. Add the breaded pork and deep-fry, turning once, until golden brown, about 4 minutes.
Spread the tonkatsu sauce on 2 slices of bread. Top with the fried pork, more tonkatsu sauce and then the shredded cabbage. Spread mustard on the other 2 slices of bread and close the sandwiches. Cut in half.