3 tsp. sugar
1/2 tsp. salt
1 tsp. dry mustard
1 egg yolk
2 tbsp. vinegar
1 c. mineral oil

(May substitute lemon juice for vinegar.)

Select a bowl just large enough for the beater. Use rotary or electric beater. Combine dry ingredients and egg yolks. Add 1 tablespoon vinegar. Add 1 tablespoon of oil and beat in thoroughly until no film or drops of oil remain. This emulsion forms the basis of a successful mayonnaise. (I suppose you have made mayonnaise so you know how important it is to get this first part to come out right, the rest goes easy.) Scrape edge of bowl frequently.

Now add 2 more tablespoons of oil and beat as before. Add 3 tablespoons of oil and beat. Add remaining oil, about 1/4 cup at a time, beating until all is blended before more is added. Add remaining vinegar. If oil separates, start with another yolk and add dressing gradually, beating constantly. (I have had to start with a second yolk a few times so it can be remedied if it fails.) It is important to keep the beater going steady.