Thanks to everyone who's tried this!
My husband, Numao, has been eating this sandwich for years since he was little. Try it out with different toppings and twists, and find your own secret recipe!
This sandwich is delicious with chopped pickles and black olives. Don't massage your cabbage and onion slices with salt or let them sit in water -- that's the key to a crunchy sandwich!
Enjoy Japanese food around the world.