Preheat oven to 375 degrees F. For crust, in a small mixing bowl combine graham cracker crumbs, pecans or walnuts, flour, and the 1 tablespoon sugar. Stir in melted butter or margarine. Toss to mix well. Press mixture onto the bottom and up sides of a 9-inch pie plate. Bake for 8 minutes. Cool on a wire rack.
For filling, in a medium saucepan combine the 1/2 cup sugar, cornstarch, and gelatin; stir in milk. Cook and stir over medium heat until thickened and bubbly; cook and stir for 2 minutes more. Place sour cream in a medium mixing bowl. Gradually stir hot milk mixture into the sour cream; stir in vanilla. Cover with plastic wrap and chill in the refrigerator for 1 hour, stirring once or twice.
Stir berries into the sour cream mixture. Turn filling into the cooled crust. Cover and chill at least 6 hours or up to 24 hours. Garnish with additional berries, if desired. Makes 8 servings.