How to Make It
In a food processor, pulse the flour with the salt. Add the butter and pulse just until pea-sized clumps form. Drizzle in the ice water and pulse just until the pastry is evenly moistened. Turn the pastry out onto a work surface and pat it into a disk. Wrap the pastry in plastic and refrigerate until firm, at least 30 minutes.
Preheat the oven to 375°. On a lightly floured surface, roll out the pastry a scant 1/4 inch thick. Fit the pastry into an 11 1/2-inch tart pan with a removable bottom and trim the overhang. Using the pastry scraps, patch any cracks in the shell. Refrigerate for 30 minutes.
Using a fork, prick the bottom of the tart shell several times. Line the shell with parchment paper and fill with pie weights or dried beans. Bake in the lower third of the oven for 30 minutes, or until the pastry is set. Carefully remove the parchment paper and weights and bake the shell for about 22 minutes longer, until golden and firm. Lightly brush the hot pastry shell with the egg white until thoroughly coated, being careful to fill any holes or cracks.
In a large bowl, using an electric mixer, beat the eggs with the sugar at medium speed until light and frothy, about 2 minutes. Beat in the maple syrup and vanilla. Add the flour and salt and beat for 1 minute longer. Beat in the butter.
Reduce the oven temperature to 325°. Set the tart pan on the oven rack and carefully pour the filling into the shell. Sprinkle evenly with the pecans. Bake the tart for about 28 minutes, until the filling is just set in the center. Transfer the tart to a rack and let cool completely.
Remove the ring from the tart pan. Slide the tart onto a cake plate and serve.
Vanilla ice cream.