Hot Mustard Sauce
Recipe 1: Melt 3 oz.of butter in a double saucepan, and the moment it is melted, mix in a generous tablespoonful of white continental mustard, salt, pepper, and a teaspoonful of mild or wine vinegar: whip, and serve at once.
Recipe 2: Make a roux by melting 2 tablespoonfuls of butter and vinegar and stirring in the same quantity of flour; do not let it brown.
Add 1 glass of hot water (or preferably hot stock) and stir over a gentle heat for 5 minutes.
Keep the saucepan hot in a shallow vessel containing boiling water whilst you bind the sauce by adding to it 2 yolks of egg beaten with 2 table-spoonfuls of French mustard and 1 teaspoonful of vinegar.
Whip together, and serve.
When you are adding the hot stock, you could also put in a pinch of chopped mixed herbs or a tablespoonful of tomato puree.