In a large bowl, add the flour, salt, sugar and whisk together.
Grate the butter over the bowl, and gently mix together with the flour. Make sure all the butter has been coated with flour.
Add the sour cream and mix until dough comes together. It should feel sticky but not unmanageable.
Divide the dough into two sections and pat down into a round. You can go ahead and roll out the bottom crust now and add it to the pie pan. Refrigerate while the filling is being made.
For the filling
In a small bowl, whisk together the sugar, salt and flour
In a medium saucepan, squeeze the muscadines and drop the pulp into the pan. Add the hulls to a medium size bowl. Add 1/4 cup water to the pan with the pulp and turn to medium heat. Cook the pulp about 5 minutes or so, mashing with a potato masher to extract the juice. Put the cooked pulp into a sieve over the bowl of hulls, and squeeze as much of the juice as possible through.
Put the hulls and juice mixture into the saucepan and cook for about another 5 minutes or so to soften the hulls. Add the sugar mixture and mix together and cook for another minute at a low boil. You'll see the mixture thicken quickly. Remove from heat and set aside to cool.
Assemble the pie
Remove the pie pan from the fridge and add the filling. Dot the top with the butter, cut into small slivers. Roll out the top pie crust and place on top, seal the edges and cut vents in the top. Brush with an egg wash. If desired, you can also do a lattice top pie crust.
Bake for 10 minutes at 400 then reduce heat to 350 and bake for another 30-50 minutes until pie crust is golden brown and the filling is bubbling up.
Remove from oven and let cool completely. If you slice into it while the pie is still warm, the pie will be a bit runny. It sets up as it cools.