Brown onion in butter
Blend in curry powder
Slowly boil the soup for 5 minutes.
Strain the soup.
Slowly add chicken stock and keep stirring until slightly thickened
Boil the soup again and stir in Groninger mustard.
Whisk 2 egg yolks and 4 tablespoons of cream. Add 4 tablespoons of the hot soup.
Add the mixture to the soup, stir forcefully and take the pan directly off the heat source.
Add smoked bacon bits / lardons and add them to the soup.