Preheat oven to 400 degrees. Line a 9 inch pie plate with pastry. If using a frozen pie crust, it isn't necessary to thaw before cooking. Trim, seal and flute edges; set aside. In a large bowl, combine the sugar, flour and salt.

In a large bowl, beat the buttermilk, eggs, butter, lemon juice, lemon peel and vanilla. Add to sugar mixture and mix well. Pour into crust. Sprinkle with nutmeg.

Bake at 400° for 10 minutes. Reduce temperature to 325°; bake 40-45 minutes longer or until a knife inserted near the center comes out clean. Cool on a wire rack. Store in the refrigerator.

Meanwhile, make the blueberry topping by whisking together the preserves and water in a small saucepan. Cook over medium heat until melted. Strain through a sieve, add the blueberries and stir to coat. Add blueberries to the top of cooled pie.