Warm up the milk. Whisk yolks in a bowl. Gradually embezzle milk. Stir in yoghurt and heat the mixture on a warm water bath while stirring constantly. Season with salt and pepper. Chop the gherkins and stir in. Keep sauce warm
Peel and chop the shallot. Boil up with stock, wine and spices. Let the fish fillets simmer for about 6 minutes at low heat. Serve with sauce