Preheat oven to 350 degrees.
In a mixing bowl, cream butter and sugar together until pale in color. Add eggs one at a time until well combined. Add flour, cornmeal and salt and combine. Add buttermilk, baking soda, vanilla and vinegar and stir until well combined.
Pour filling into pie shell and bake until browned and the custard has set, 45-50 minutes.
Allow to cool at least 30 minutes before slicing.
*Try Lomah Dairy and Wagon Creek Creamery for local buttermilk