Cook the frozen croquettes in the toaster oven per the package (the bake-not-fry kind needs no oil and comes out crisp).
Meanwhile, make the miso soup. If instant, just add hot water.
Separate the egg into yolk and white. Mix the leftover white into the miso soup so nothing is wasted.
Mix the natto with its sauce and mustard, scatter green onion, and set the yolk in the center (use a fresh egg and eat right away; swap in a fried egg if raw is not for you).
Lay cabbage on a plate, top with the croquettes and add sauce.
Arrange with rice, miso soup and pickles on a tray for a home-made set meal.