Vinegar Pie
["1 (9-inch) pie crust, baked", "1 c. white sugar", "3 egg yolks", "1 Tbsp. unsalted butter", "3 Tbsp. distilled white vinegar", "6 Tbsp. white sugar", "1/4 c. sifted all-purpose flour", "1 c. water", "1/8 tsp. salt", "1/4 tsp. lemon extract", "3 egg whites"]
["Mix flour with 1/2 cup sugar. Add water gradually and cook on top of double boiler for 15 minutes, stirring constantly or until thick. Combine remaining 1/2 cup of sugar with egg yolks and salt and mix well. Add the hot flour mixture to the yolk mixture. Return to double boiler and cook 3 more minutes or until mixture is thick. Add butter, extract and vinegar. Mix well and remove from heat.", "Place plastic on top of custard."]
["pie crust", "white sugar", "egg yolks", "unsalted butter", "white vinegar", "white sugar", "flour", "water", "salt", "lemon extract", "egg whites"]