Creamy mustard sauce

Ingredients

→ 4 TEASPOONS MILD MUSTARD
→ 3 TABLESPOONS UNSWEETENED YOGURT
→ 2 TABLESPOONS CREAM (10% FAT CONTENT)
→ 100 G OF MAYONNAISE
→ 1 HARD-BOILED EGG

Chop the egg, mix with mayonnaise, yogurt, cream and mustard.

Fill the fish with the resulting sauce.