Preheat oven to 450°.
Fit the dough into a 9-inch round removable-bottom tart pan, and pierce dough with a fork; bake at 450° for 10 minutes or until lightly browned. Cool completely on a wire rack.
Place 1/4 cup sugar, flour, and salt in a medium, heavy saucepan. Gradually add milk, stirring with a whisk. Scrape seeds from vanilla bean; add seeds and bean to milk mixture. Cook over medium heat until thick and bubbly (about 5 minutes), stirring constantly.
Place egg in a large bowl. Gradually stir hot milk mixture into egg. Return milk mixture to pan. Cook 2 minutes or until thick and bubbly, stirring constantly. Spoon custard into a small bowl. Place bowl in a larger bowl filled with ice. Cool 20 minutes or until thoroughly chilled, stirring occasionally. Discard vanilla bean.
Spread chilled custard into bottom of prepared crust. Arrange the peach slices spoke-like on top of chilled custard. Sprinkle 1/3 cup sugar evenly over peach slices. Holding a kitchen blow torch about 2 inches from the top of peach slices, heat the sugar, moving the torch back and forth, until the sugar is melted and caramelized (about 3 minutes).