Vinegar Pie
["3 Tbsp. vinegar", "1 c. sugar", "1 Tbsp. butter", "4 Tbsp. flour", "1 c. water", "2 egg yolks"]
["Mix flour with half of sugar.", "Add boiling water and cook 15 minutes.", "Add rest of sugar and beaten egg yolks; cook a few minutes longer.", "Add butter, vinegar and 1 teaspoon lemon extract, if desired."]
["vinegar", "sugar", "butter", "flour", "water", "egg yolks"]