MMMMM-----------------------FOR THE SAUCE---------------------------- 2 Cooked beetroot; skined 1 5 1/4 ounces natural yogurt; -(150g) 1 tb Horseradish sauce; (15ml -spoon)MMMMM-------------------------TO GARNISH------------------------------ 2 Spring onions; sliced 1. Lay the herring fillets in a shallow dish, skin side down and cover them with sliced onion. Sprinkle on the peppercorns, and pour the vinegar over the dish. Cover the dish and refrigerate for 2 days. 2. Drain the herring and arrange them on a serving plate. Grate the beetroot and mix it with the yogurt and horseradish sauce. 3. Garnish the herring with spring onions, and serve the sauce separately. NOTES : If you are making your own Bismarck herring, you do need to start preparation for this dish two days in advance. You could, of course, cheat and buy either Bismarck or rollmop herrings in jars or from the delicatessen counter, in which case this dish would take about 10 minutes to prepare at the most.