If using salt herrings soak in cold water for several hours, fillet —removing all bones. If using roll-mop herrings divide into 2 fillets. Mix chopped anchovy fillets with egg yolks, butter, pepper and little lemon juice. Put on to the herring fillets and roll firmly. Dip each end in finely chopped egg white. Sprinkle with lemon juice. Garnish with slices of lemon, sliced gherkin, diced beetroot and parsley.