Combine 1 1/2 cups of flour and the salt in a food processor. Pulse to blend. Add the pieces of butter and then pulse until the butter is the size of lentils or small peas.

Add 2 tablespoons of ice water and pulse a few times. Add more ice water, about 1 teaspoon at a time, while pulsing, until the dough begins to clump together.

Turn the dough out onto a floured surface and knead just until the dough holds together. Shape it into a disk, wrap with plastic wrap, and refrigerate for 20 to 30 minutes.

Roll the chilled dough out and fit it into a pie plate. Crimp the edge as desired.

Preheat the oven to 375 F.

Line the crust with foil and fill with pie weights or dried beans or rice. Bake the crust for 15 minutes. Remove the weights and foil and prick the bottom of the crust all over. bake for 5 minutes longer. Remove the crust to a rack.

Reduce the oven heat to 325 F.

In a mixing bowl with an electric mixer, beat the eggs and sugar until light and lemon colored. Beat in the 2 tablespoons of flour, then add the buttermilk, melted butter, lemon zest, lemon juice, and vanilla. Blend thoroughly.

Pour the filling mixture into the partially baked pie shell.

Bake in the preheated oven for 45 to 55 minutes, or until a knife comes out clean when inserted in the center. The center of the filling will be slightly wobbly.