This enchanting fish dinner is the quintessential use for shio koji, an incomparable salty and sweet condiment made from the same malted rice used to ferment miso, sake and soy sauce. Slideshow: Kale Recipes
Pat the fish dry with paper towels, then rub all over with shio koji. Cover and refrigerate for 2 hours.
Warm 1 tablespoon of the butter in a skillet over medium heat. Add the chopped kale and toss briefly, then add the vinegar. Toss until the kale is softened and bright green, then toss in the togarashi and a dash of salt. Set aside.
Warm the remaining 4 tablespoons butter in a skillet over medium heat. Remove the fish and wipe away the excess shio koji. Combine the potato starch and white pepper, then dredge the fish in the starch. Pan-fry the fish, in batches if needed, about 3 minutes per side. The fish is done when it is just starting to flake. Serve the fish over a bed of the sautéed kale.