Makes about 2 ½ cups

1 whole egg or 2 egg yolks

1/2 teaspoon dry powdered mustard

1/2 teaspoon sugar

1/2 teaspoon salt

Juice of ½ a lemon

2 ½ cups of vegetable oil

Put the first 5 ingredients in a bowl and with a rotary beater, blend until thick and creamy.  Then begin to add the oil, VERY slowly, no more than 1 tablespoon at a time, incorporating thoroughly after each addition.  After using about half of the oil the mixture will thicken.  After that you may begin adding the oil a bit faster, about 1/4 cup at a time, but always incorporating thoroughly after each addition.  When all the oil is used, taste and adjust the seasonings. This will keep in the refrigerator for at least a month.

I cannot impress upon you enough how vital it is to add the first half of the oil VERY, VERY slowly.