1. Preheat your oven to 375°F (190°C).
2. In a mixing bowl, combine flour and butter. Mix until it resembles coarse crumbs.
3. Gradually add ice water, mixing until dough forms. Divide dough in half, wrap in plastic, and refrigerate for 30 minutes.
4. Roll out one half of the dough and fit into a pie dish. Set aside.
5. In another bowl, mix huckleberries, sugar, cornstarch, lemon juice, lemon zest, and vanilla extract.
6. Pour the filling into the pie crust.
7. Roll out the second half of the dough and place over the filling. Crimp the edges to seal.
8. Cut a few slits on the top crust to allow steam to escape.
9. Bake for 60 minutes or until the crust is golden brown and the filling is bubbly.
10. Let the pie cool before serving.