Photo: Kent Wang (CC BY-SA 2.0) via Wikimedia Commons · source
A thick, juicy pork cutlet in light panko, brushed with sweet-sharp tonkatsu sauce, pressed between soft milk bread with the crusts off. Wrapped and rested 5 minutes, it slices into clean, neat rectangles.
1 tbsp soft butter mixed with 1/2 tsp Japanese mustard (karashi) or Dijon
Finely shredded cabbage (optional)
How to make it
Prep the pork (5 min): Make a few small cuts through the fat edge so it doesn't curl. Pound lightly to an even thickness, then season with salt and pepper.
Bread it (5 min): Dust with flour, dip in egg, then press firmly into panko on all sides. Rest 5 minutes so the crumb sets.
Fry (10 min): Heat 3 cm (1 1/4 in) oil to 170 C (340 F). Fry the cutlets 3 minutes a side until deep golden and 63 C (145 F) inside. Drain on a rack 3 minutes; they keep cooking.
Sauce it (1 min): Dip or brush each cutlet on both sides with the sauce.
Assemble and press (8 min): Spread the bread with the mustard butter. Add cabbage if using, then the cutlet, then the top slice. Wrap tightly in plastic and press under a plate 5 minutes. Cut off the crusts and cut into 3 rectangles.
Tips
Pressing is what makes it look like a Tokyo depachika sando.