Salad Dressing

Yolks of 7 eggs, 1 tablespoonful of mustard; 1 tablespoonful of salt; 1 tablespoonful of butter (or oil); 1 tablespoonful of sugar; 1 cupful of milk; 1 cupful of vinegar. Mix the mustard, salt, sugar, and butter, until smooth; add the beaten yolks of the eggs, the vinegar (warm), and lastly the milk; cook in a double boiler until thick.