Cut the cod in half or thirds. Place on a flat sieve and salt both sides, then let sit for about 10 minutes.
Thoroughly wipe off excess moisture from the cod with paper towels. Using a tea strainer, lightly coat both sides of the fish with flour.
Thinly slice the onion, julienne the carrot, remove the stem end and seeds from the green pepper and thinly slice. Cut off the very end of the root from stems of the shiitake mushrooms, then thinly slice both the stems and tops.
Heat vegetable oil in a frying pan, add the cod, and fry until both sides are golden brown. Transfer to a large plate.
Wipe excess oil from the frying pan with a paper towel, add oil, heat, then sauté the vegetables.
Once the vegetables are tender, mix in the dashi soup stock, vinegar, soy sauce, and light brown sugar.
When it comes to a boil, turn off the heat, pour in the katakuriko slurry, and briskly mix until even.
Turn on the heat, continue stirring with a wooden spatula, then turn off heat once it simmers to a thick sauce. Pour over the cod, and serve.
Story Behind this Recipe
I wanted to increase my repertoire for cod, since my daughter loves it, so I came up with this version with a veggie-packed sweet vinegar ankake sauce.
Prepping the cod well eliminates the unpleasant fishy smell and helps keep it from breaking apart while cooking. Thinly slicing the green pepper horizontally will soften its texture. If you will prepare your katakuriko slurry with the method shown here, you'll be able to avoid lumps.