Lemon Mayonnaise

For fruit, chicken, or seafood salads. Combine cornstarch, mustard, and salt in the top of a double boiler. Combine water and beaten eggs. Slowly add to cornstarch mixture, stirring constantly, until smooth. Cook over simmering water for 5 minutes, stirring constantly. Very slowly stir in the lemon and vinegar. Continue cooking and stirring over simmering water for 10 more minutes. Remove from heat. Add the sweetener; mix well. Pour into a pint jar, cover, and store in refrigerator. Stir well before each use