Lightly season the cod with salt, pepper, and sake.
Julienne the vegetables.
Add the water, soy sauce, mirin, sugar, and salt to a pot and bring to a gentle boil. Turn off the heat.
Dust the cod from Step 1 lightly with flour. Heat vegetable oil in a frying pan and pan-fry the cod on both sides until well browned.
While the cod is cooking, add the vegetables from Step 2 to the pot from Step 3. When the vegetables are cooked, add the katakuriko dissolved in water and stir to thicken.
When the cod is done cooking, pour the an-sauce from Step 5 on top. Done.
Story Behind this Recipe
I took some hints from a recipe for fried flounder with vinegar an-sauce to make a healthier fish recipe.
You can make the vegetable an-sauce ahead of time, but it's better not to heat the green pepper until just before the cooking is done or the color won't be so green. You could this recipe with other kinds of fish, too.