Salt and pepper the Whiting fillets.
Wholesale cut of.
Melt the butter in a saucepan and stir in the flour.
Add 10cl of water.
Off the heat, pour red wine, mustard and finely chopped onion.
Pour the remaining water and stir carefully.
At this time, add the pieces of fish.
Cover your saucepan and simmer 30 minutes on low heat.
Just before serving, stir yogurt to your dish.
Stir! It is ready!