Grilling kasuzuke

I just bought some black cod kasuzuke at the Japanese grocer because it sounded interesting to try. Anyone want to chime in on the best way to prepare it? My plan right now just includes soy sauce, green onion, mirin, hot oil. Is there a typical side dish served with it? Also, would you wash off the marinating sauce of sake lees or kind of grill the fish in its own juices, as it were? Thanks for any help.
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