1/4 c. sugar
2 tsp. all-purpose flour
1 tsp. dry mustard
1/2 tsp. salt
1/4 c. water
1/4 c. vinegar
2 eggs, beaten
1 tbsp. butter

Combine first 4 ingredients in a saucepan; blend well. Gradually stir in water and vinegar. Add eggs, beating well with a wire whisk. Add butter. Cook over medium heat until mixture comes to a boil, beating constantly. Cover and chill.