Boil the potatoes and let them cool. Then peel and cut into slices.
Peel and chop the onions.
Put all the ingredients for the first sauce in a saucepan and bring to the boil while stirring.
Pour over the potato slices and stir in carefully.
Put the cream and milk in a bowl, stir in the mayonnaise. Add sugar, herb salt and the dill tips and stir well. Season to taste with a squeeze of lemon juice.
Pour the second sauce over the potatoes and stir in carefully.
The potato salad tastes best if you let it steep overnight.