Ingredients

1/2 cup sugar 

1/4 cup Coleman's mustard powder 

2 large egg yolks 

1/2 cup red-wine vinegar 

3/4 cup creme fraiche, or sour cream 

Preparation

Place sugar and mustard in the top of a double boiler, and whisk to combine. When well combined, whisk in egg yolks and vinegar. Cook over simmering water, stirring occasionally, until thick enough to form ribbons when drizzled from a spoon, 10 to 15 minutes. Remove from heat, and allow the mixture to cool. When cool, fold in the creme fraiche. Refrigerate in an airtight container until ready to use.