1. In a large bowl, combine the flour and salt. Cut in the cold vegan butter until the mixture resembles coarse crumbs. Gradually add the ice water, mixing just until the dough comes together. Divide the dough in half, shape into discs, wrap in plastic, and refrigerate for at least 30 minutes.

2. In a large skillet, heat the olive oil over medium heat. Add the onion and garlic and sauté until softened, about 5 minutes.

3. Add the diced potatoes, carrots, and celery. Cook for 10 minutes, stirring occasionally, until the vegetables are slightly tender.

4. Stir in the frozen peas, vegetable broth, thyme, sage, and black pepper. Bring to a simmer and cook for 15 minutes, or until the vegetables are tender.

5. In a small bowl, whisk together the coconut milk and cornstarch. Pour this mixture into the skillet, stirring constantly, until the filling thickens, about 2-3 minutes.

6. Preheat the oven to 375°F (190°C).

7. On a lightly floured surface, roll out one disc of dough to fit a 9-inch pie dish. Transfer the dough to the pie dish and trim any excess.

8. Pour the filling into the pie dish. Roll out the remaining dough for the top crust. Place the top crust over the filling and crimp the edges to seal.

9. Cut several slits in the top crust to allow steam to escape.

10. Bake for 35-40 minutes, or until the crust is golden brown and the filling is bubbling.

11. Allow the pot pie to cool for 10-15 minutes before serving.