How to Make It
Using kitchen shears, score the fat at the edges of the chops at 1-inch intervals, about 1/4 inch deep.
Put the flour, eggs and panko in 3 separate shallow bowls. Season the flour with 1 teaspoon each of salt and pepper. Season the pork cutlets with salt and pepper and coat them with flour, tapping off the excess. Dip the cutlets in the beaten eggs and then in the panko, pressing to help the panko adhere.
In a large skillet, heat 1 inch of oil to 360°. Fry 2 pork cutlets over moderate heat, turning once, until golden brown and white throughout, about 4 minutes. Drain on paper towels. Transfer to a cutting board and season with salt. Repeat with the remaining cutlets.
In a small bowl, whisk the mustard powder with 3 tablespoons of water until smooth.
Slice the tonkatsu into 3/4-inch strips and transfer to plates. Serve with the cabbage, Japanese mustard, tonkatsu sauce and lemon wedges.
Japanese mustard, which you make by combining equal parts Japanese mustard powder and water, is spicier and more pungent than most other prepared mustards. Tonkatsu sauce is available at Asian markets and from amazon.com.