In a mixing bowl, combine flour, sugar, and butter. Mix until crumbly.

Add egg yolk and ice water, mixing until the dough forms. Shape into a disk and refrigerate for 30 minutes.

Roll out the dough on a floured surface and fit it into a tart pan. Prick the bottom with a fork.

In a bowl, toss apricots with sugar, lemon juice, cornstarch, and vanilla until well coated.

Arrange the apricot mixture evenly over the crust.

Preheat the oven to 350?F (175?C). Bake the tart for 35-40 minutes, or until the apricots are tender and the crust is golden.

Allow to cool before serving.