Use cold or frozen butter for this. Grate it on a coarse grater into small pieces (1/2 cup + 1 tbsp worth)
Add vinegar, salt and flour. Mix together just until it becomes crumbly. Add sugar to this and mix just to combine.
Add active sourdough starter to the flour mixture. Combine and then knead the dough a few times with your palms just enough to incorporate, no longer or it will become tough.
Cut dough in half so you have a bottom and top layer, roll out just enough or use palms to press flat. Then press half into your sprayed pie tin covering the bottom and up sides.
Add your favorite filling inside. Roll or press out other half and place on top, crimping sides together if they are able to touch. Cut 2-3 small slits at the top to vent. Bake at the temperature and timing your pie recipe calls for.
** if you want to blind bake the bottom crust first, do so for 10 minutes in a preheated oven at 350 degrees F, then add filling, add top crust and bake according to your recipe directions. If adding cold filling, blind bake the bottom, allow to cool completely, then add cold pie filling.