Satsivi iz Ryby

Walnuts grow well in Georgia and are the basis of the famous Georgian satsivi sauce. This is served with meat or chicken or, as in this recipe, with fish. Walnuts are rich in oil, and the sauce goes best with a fish of firm, white and lean flesh; but the choice of fish is left to the cook. I recommend turbot, which is so good in the Black Sea, or sea bass or large gurnards or hake; but I would not exclude some rather richer fish such as the bonito or salmon trout (of which a species survive