- 1/2 cup margarine, softened
- 1 1/2 cups potato flour
- 1/4 cup ice water
- 1 pinch salt
- 4 cups blackberries
- 1 cup white sugar
- 1/3 cup potato flour
- 2 tablespoons lime juice
- 1/4 cup margarine, melted and divided
- Beat 1/2 cup margarine, 1 1/2 cups potato flour, ice water, and salt together in a bowl with an electric mixer until mixture is large crumbs. Form into a ball of dough; chill in refrigerator for 1 hour.
- Stir blackberries, sugar, 1/3 cup potato flour, and lime juice together in a bowl.
- Preheat oven to 350 degrees F (175 degrees C).
- Separate dough into two equal halves. Roll each half with a rolling pin to 12 inches in diameter. Press one crust in a 9-inch pie pan. Scoop blackberry filling into the prepared pan. Drizzle 3 tablespoons margarine over blackberry filling.
- Lightly press the other pie crust on top of the blackberry filling and seal the edges to the bottom layer's edges. Brush top crust with remaining 1 tablespoon melted margarine. Cut 2 or 3 slits in the top crust to allow steam to escape during baking.
- Bake pie in the preheated oven until crust is golden brown and blackberries are bubbling, about 40 minutes.