To make the crust, mix the flour, sugar, and salt in a large mixing bowl. Add the butter and use a pastry cutter or two knives to cut the butter into the flour, until the pieces of butter are about the size of peas. Alternately, you can put the flours, salt, and sugar into a food processor, add the butter, and pulse until the ingredients are combined and the butter is the size of peas.
Mix the ice water and vinegar. Add the water into the flour mixture in a thin stream, using a spatula to mix as you go. As soon as the dough holds together without being wet, and it easily sticks together when you squeeze a small amount in your hand, it's ready. If your dough is too crumbly and isn't holding together, add additional ice water by the tablespoon until it does. Transfer the dough to a floured work surface and shape it into a disk. Wrap it in plastic wrap and refrigerate for at least 2 hours. At this point, you can keep the dough in the fridge for up to 2 days or freeze it for later use, if you like.
When the dough has finished chilling, preheat your oven to 375F. Flour a work surface and rolling pin.
On the floured work surface, roll the dough into a circle about 1/4 inch thick and about 12 inches in diameter. Gently transfer this circle of dough to a pie dish. Trim and crimp the edges, then use a fork to prick the bottom of the crust. Cover the crust with a sheet of parchment paper and fill it with dry beans (any are fine) or pie weights for blind baking. Blind bake the crust for 10-12 minutes, or until the edges of the crust are just barely golden. Remove the par-baked crust from the oven, discard the beans, and remove the parchment sheet.
While the crust blind bakes, blend all of the filling ingredients together in a food processor or blender. Blend for a full 2-3 minutes, or until the filling is silky smooth.
Remove the crust from the oven. Allow it to cool for 10 minutes. Then, pour the filling into the crust. Return it to the oven and bake for 45 minutes, or until the crust is browning at the edges and the filling is jiggly, but set at the outer edges. I recommend using a commercial or homemade foil pie crust shield to protect the edges from browning too much during baking, but it's not absolutely necessary (browned pie crust still tastes good!). Remove the pie from the oven. Allow it to rest in a cool place for at least 5 full hours before slicing. Alternately, you can chill it in the fridge overnight (or up to 3 nights) before serving. Cut into slices, top with tofu whipped cream if desired, and enjoy!