Peel the onions. Wash, quarter and core the apples.
Finely dice the cucumber, herring fillets, hunting sausage and apples. Put everything together, drizzle with lemon juice and mix well.
Peel the eggs and cut them roughly into pieces. Cut the onions into thin rings. Add both to the cubes and mix well again.
Mix yoghurt and mayonnaise together and mix thoroughly with the salad ingredients. Season to taste with a pinch of sugar, salt, pepper, capers and a dash of caper stock.
Let the Altmark herring salad soak for at least 4 hours, or even better overnight.