Pat the herring dry on paper towels. Put the allspice, sandalwood, cloves, ginger, hops, bay, salt petre and citric acid in a mortar and lightly crush with the pestle. Mix with the sugar and salt – this is the ‘cure’.
Cut the fish into 5 cm-wide pieces. Sprinkle some of the cure on the base of a large resealable glass or ceramic jar and place a layer of fish on top. Continue layering. M