Prepare Tart Pastry. Preheat oven to 450 degrees F. Wrap the rolled-out pastry around a rolling pin. Using pin, ease pastry into a 9-inch tart pan with removable bottom, taking care not to stretch the pastry. Press pastry into fluted sides of tart pan. Trim edges even with the pan. Line pastry with a double thickness of foil. Bake for 8 minutes. Remove foil. Bake 5 to 6 minutes more or until crust is golden. Cool on wire rack. Reduce oven temperature to 350 degrees F.
Meanwhile, finely shred 4 teaspoons peel from lemons. Set aside. Squeeze enough juice from lemons to measure 6 tablespoons; set aside.
In medium bowl combine sugar and flour. Add eggs. Beat with electric mixer on medium to high speed for 3 minutes or until mixture is light in color and slightly thickened. Stir in lemon peel, lemon juice, butter, and vanilla. Pour into pastry shell. Place tart pan on a baking sheet.
Bake 20 to 25 minutes or until filling is set and lightly browned. Cool on a wire rack.
To serve, remove sides of pan, and top tart with Oven-Candied Lemon Slices. Makes 8 servings.
In medium bowl cut butter into flour until pieces are the size of small peas. In a small mixing bowl combine egg yolk, and 1 tablespoon ice water. Gradually stir the egg yolk mixture into the flour mixture. Add 2 to 4 tablespoons more water, 1 tablespoon at a time, until all the dough is moistened. Shape into a ball. If necessary, cover dough with plastic wrap and chill in refrigerator for 30 to 60 minutes or until dough is easy to handle. On a lightly floured surface, roll out dough on an 11-inch circle. Use to prepare Lemon-Vanilla Tart.
Line a 15x10x1-inch baking pan with parchment paper. Cut lemons crosswise into 1/8-to 1/4-inch-thick slices. Arrange in a single layer on pan. Sprinkle lemon slices with sugar. Bake in preheated 275 degree F oven 45 to 50 minutes or until lemons are almost dry and covered with sugary glaze. While still warm, loosen slices from paper to prevent sticking.