Add white vinegar to make 2 cups total of sugar and vinegar.
Soak herrings overnight in cold water in cool place. Fillet fish by removing small bones and skin. Rinse and drain. Cut fillets into thin slices. Place in layers with onion and spices. Mix vinegar and sugar and pour over. (This should cover fish pieces.) Remove red peppers from spices.
Fish will be completely pickled in about 2 weeks. However, many Scandinavian people prefer to eat the herring 3-4 hours after preparing. Place in refrigerator for storing.
