1. Preheat oven 425 degrees F. For sauce, heat veggie broth in a pot until it starts to boil. Add cumin and lower heat to medium. Add flour slowly and stir until thickened. Lower heat to low and let sit.
2. To make crust, mix flour and salt together in bowl. Cut in margarine until dough looks crumbly. Stir in water. Roll dough into a ball. Divide in 1/2.
3. Roll out 1/2 of the dough until large enough to line a 9" pie plate. Roll out second 1/2 and set aside. Fill pie shell with veggies and potatoes.
4. Pour thickened broth over veggies and cover with top layer of crust, making sure to seal tightly. Cover outside edge of crust with foil. Remove foil 15 minutes before pie is done.
5. Put on middle rack in oven and bake for 30 minutes or until top of the crust has lightly browned.