In a high-speed blender or food processor, combine the flour, powdered sugar, salt, and chopped vegan butter. Blend until the butter is broken into tiny pieces.

Gradually add the iced water, 3 tablespoons at a time, mixing after each addition. Stop adding water once large clumps form.

Lightly flour a flat surface and transfer the dough onto it. Gently press and knead until smooth. Form into a ball and divide into two pieces. Flatten each piece to about an inch in thickness. Wrap and refrigerate for an hour.

When ready to make the pie, roll out the dough evenly. Place one of the dough balls into an 8-inch pie pan. Cut the second piece into thin strips and set aside.

In a large mixing bowl, mix the sugar and cornstarch until combined. Add the blueberries and lemon juice. Mix well to fully incorporate.

Assembling and baking the pie:

Preheat the oven to 350F.

Pour the blueberry filling into the pie crust, ensuring the juice doesn't touch the sides. Arrange the dough strips in a criss-cross pattern over the top of the pie. Optionally, brush with melted butter or milk.

Bake for 50-60 minutes, until golden on top. Remove from the oven and let sit for 10 minutes before slicing and serving.