Preheat oven to 350 degrees.
Filling: In bowl combine sugar, flour, cornmeal and salt. Add softened butter to dry ingredients and mix until crumbly, pour in beaten eggs, and mix on medium/high speed until smooth and creamy, 3+ minutes.
In large measuring cup combine buttermilk, baking soda, vanilla, and vinegar whisk together, gradually add to the sugar/egg mixture beat for an additional 3 minutes.
Roll out pie crust, lay into a 9" pie plate, crimp the edges, poke bottom of crust with a fork a few times, pour in filling. Bake for 20 minutes uncovered, then cover with a sheet of aluminum foil to prevent crust from burning, bake for an additional 25-30 minutes. Let cool completely.
Praline: In saucepan combine brown sugar and cornstarch turn heat on medium, whisk in Karo syrup. Cook until mixture begins to bubble up, cook for 3 minutes add in vanilla and coffee, continue to cook for another 2 minutes, remove from heat stir in coconut and chopped pecans. Stir vigorously to cool and to create a airy texture, do this until your arm hurts! For me that's about 3 minutes. Let cool for 10 minutes then spoon over the top of the Buttermilk Pie, carefully spreading to cover the top. Refrigerate, or immediately dig in!