Mustard Sauce - cooking recipe

Ingredients

1 1/2 tsp. dry mustard
1 Tbsp. flour
1 c. sugar
pinch of salt
1/2 pt. thin cream
1 egg, separated
1/2 c. vinegar

Preparation

Mix dry ingredients with cream, vinegar and egg yolk.
Cook until thick.
Beat egg white until very stiff and fold into cooked mixture.