1 1/2 tablespoons flour
1 teaspoon dry mustard
1 tablespoon sugar
2 egg yolk, beaten
2 tablespoons butter, melted
1/4 cup milk
1/4 cup vinegar
Salt to taste
Mix flour, mustard, and sugar together in heavy saucepan. Add egg yolks, butter, milk, vinegar, and salt to taste; stir constantly over low heat until thick. Cool.