Directions

1. Preheat oven to 350 degrees F (175 degrees C.) In a medium bowl, mix graham cracker crumbs, 1/4 cup sugar and melted butter until well blended. Reserve 1/4 cup of crumb mixture and set aside. Press remaining mixture into a 9 inch deep dish pie pan. Bake in preheated oven for 8 to 10 minutes, or until lightly browned. Allow to cool.
2. In a saucepan, dissolve cornstarch and 2/3 cup sugar in 1/4 cup cold water. Stir in grapes and bring to boil, stirring constantly. Reduce heat and simmer for 5 minutes. Remove from heat and stir in the lemon juice. Allow to cool. Spoon filling into the baked and cooled crust.
3. In a small bowl, combine sour cream, 4 teaspoons sugar and 1 teaspoon vanilla. Mix well and spread over pie. Sprinkle with reserved crumb mixture.