I grilled the marinated cod in our toaster oven. This has to be done very carefully because it is very easy to "burn".
Sake lee marinade base "Kasu-doko" 酒粕床
Sake lees: one package, 300grams, frozen.
Sugar: 3 tbs
Salt 1/2 tsp
Sake and hot water: as needed depending on how dry sake lees is (see direction).
1. I broke the sake lees in to small chunks (#1). Since my sake lee was kind of dry, I added about 50ml of hot water and covered and let it steep to soften.
2. I added miso, sugar and initially using a potato masher and then switched to a silicon spatula to mix as I added sake in small increments (probably ended up using about 100ml, #2).
3. I mixed it well until the sugar dissolved, then mixed in the miso until I attained the consistency of soft miso. The amount of hot water and sake totally depends on how dry the sake lees was to start with (#3).
4. I placed the sake lees mixture to sealable flat container (#4).
Preparation for cod:
I got two pieces of cod filet; serving for two. I washed and patted it dry using sheets of paper towel. I salted both sides and let it sit in the refrigerator for 30 minutes to 1 hour.
I dried the surface again using paper towels and placed the filets in the sake lees marinade above (making sure all the surfaces of the fish were covered, see picture below). The fish needs to be marinated at least 3 days to have a nice somewhat pungent (but not fishy) flavor.
This is after three days. I carefully scraped off the sake lees marinade. Depending on your preference, you could leave some sake lee marinade attached but it is very easily burnt. I quickly washed off and then dried the fish it by blotting with sheets of paper towel before grilling.
I grilled it using our toaster oven. Some moisture will develop during grilling so I placed a metal grate on a shallow baking pan and placed the fish 1 inch below the grilling element. I cooked one side 5-7 minutes until occasional brown spots appeared. I carefully turned it over and grilled the other side for several more minutes.
This technique can be used for other fish such as salmon but I like cod the best. Since cod or white fish does not have a strong flavor but does have a nice flaky texture, kasuzuke treatment really adds a nice albeit a bit pungent (but not fishy) flavor to the fish. This was somewhat nostalgic to me since I have not had cod kasuzuke for a long time. This is a lot of work but kasudoko can be frozen and can be used multiple times. I divided the kasudoko into two sealable containers; one for fish or meat and the other for vegetables (I am making cucumber kasuzuke as I speak). The only problem for us is to find space for it in our freezer.