From 1919:
Place in saucepan:
One cup water,
One-half cup vinegar,
Three level tablespoons cornstarch.
Dissolve starch, bring to a boil, cook five minutes. Now place in a small bowl:
One egg,
One teaspoon salt,
One teaspoon sugar,
One teaspoon mustard,
One-half teaspoon paprika.
Beat to mix. Now add six tablespoons salad oil.
Blend mixture, add to the cooked mixture. Beat hard to blend.