In a food processor, pulse together the flour, sugar, and salt. Add the butter and pulse until the mixture resembles coarse meal. Add the egg yolk mixture and pulse just until the dough can be gathered into a ball. Flatten into a 6-inch disc, wrap in plastic, and chill several hours or overnight. Let the dough soften slightly at room temperature before rolling.
Preheat oven to 350 degrees F.
On a lightly floured surface, roll the dough into a 13-inch round. Fit the dough into a 10 1/2 inch tart pan with a removable bottom. Trim the dough flush with the rim and freeze the tart shell until firm.
Line the shell with foil or parchment, and fill with pie weights, rice, or dried beans. Bake for 20 minutes until set. Remove the foil and weights and bake an additional 10 to 15 minutes until lightly golden. Remove the shell from the oven and immediately brush the hot pastry with the egg white. Set aside until ready to fill with the filling.
Hint: When rolling tart pastry, always save all the dough scraps in case you need them to repair a crack in a partially baked shell. If the pastry "bubbles up" during the baking process, gently prick the pastry with a fork to release air bubbles. Check several times and repeat if necessary. The egg white serves to seal the pastry, which is especially helpful with a liquid filling such as this. It is essential that there be no cracks or holes visible in the partially baked shell. Make any necessary repairs prior to filling.