Wash the apple, grate dry, quarter it, cut out the core. Cut apple quarter into pieces. Peel onion and cut into strips. Rinse herring, dab dry and cut into pieces.
Beat the cream and mustard until thick. Season to taste with salt, pepper and sugar. Layer all ingredients with the sauce and the cranberries in glasses. Herring salad can be prepared well the day before. Then add the sauce separately.
It goes well with farmhouse bread.