Preheat oven to 375˚F. Place the pie crust in a pie pan and let it chill in the refrigerator while preparing the filling.
Spread the chopped pecans on a baking pan and toast in the oven until slightly golden, about 5-6 minutes. Watch carefully not to burn the pecans. Let it cool.
In a large mixing owl, combine butter, brown sugar, salt, cinnamon, and flour; mix well
In a small mixing bowl, mix the beaten eggs, milk, vinegar, and vanilla extract. Pour the egg mixture into a sugar mixture. Add the pecan and stir well.
Pour the pie filling into a prepared unbaked pie shell. Decorate the top with the pecan halves. Bake in the oven for 50-60 minutes until the center of the pie comes out slightly jiggly. Let the pie cool completely on a cooling rack before you slice it.
Store the leftover pie in the refrigerator.
