Black Cod Kasuzuke

Kasuzuke is one of those preparations that sounds fancier than it is. The technique is simple: bury the seafood in a mound of sake kasu (the soft, fragrant paste left behind after sake is pressed from its fermented mash), then let it cure in the fridge. It's loaded with enzymes, natural sugars, and a bit of residual alcohol that gently break down proteins, smooth over fishiness, and coax out a nutty, umami-rich sweetness that feels almost like kitchen alchemy.

It probably dates back to the Edo period, when sake brewers realized this byproduct could be upcycled to preserve fish while enhancing its flavor. Back then, sake kasu was richer and wetter, but today's machine-pressed kasu tends to be drier. That is why I like to stir in mirin and sugar to bring back some of that moisture and sweetness. I usually add a little miso for extra umami and a little more fermented funk.

Before the cure, I salt my black cod for about twenty minutes to draw out excess moisture and partially season the fish. I'm also convinced that this helps reduce fishy odors. Once the fillets are patted dry, they go into the sake kasu mixture for at least three days, which gives everything time to really mingle. You can shorten the cure to overnight if you are pressed for time, but I recommend sprinkling a little extra salt on the fish if you're going this route. I usually cure a variety of fish over the weekend and enjoy it throughout the week. When you are ready to cook, scrape off the kasu and pan-fry or broil the fish until the surface caramelizes into golden patches with a little char at the edges.

As for the type of fish, black cod is my favorite for its buttery richness, but any oily fish works: salmon, mackerel, or even Patagonian toothfish.

Keep in mind that the alcohol won't fully cook off unless you seriously overcook the fish, so it's best to skip this for kids or for anyone avoiding alcohol.