Preparation:

1. Butter an 11-inch springform tart pan with 1 teaspoon butter and set aside.
2. Insert the chopping metal blade in the Cuisinart Food Processor. Place the flour and salt in the work bowl and pulse 5 times.
3. Remove the dough to a sheet of wax paper, shape it into a disc and refrigerate, or use the dough immediately.
4. Preheat the oven to 400°F
5. Add the butter and pulse 10 to 15 times until the butter and flour resembles a very coarse meal. Some bits of butter may be visible.
6. Add the yolk and ice water and process until the mixture just begins to form a ball.
7. Remove the dough and shape it into a disc. On a lightly floured surface, roll the dough into a circle, about 14-inches in diameter.
8. Lift the dough carefully and place it in the prepared tart pan. Fold in the excess dough and press to form thick sides.
9. Use a fork to evenly pierce the entire bottom of the dough. Freeze until the dough is firm, about 20 to 30 minutes.
10. Preheat the oven to 400°F.
11. Line the chilled pastry with foil of parchment and fill with pie weights. Bake for 12 minutes.
12. Remove the liner and weights and bake for an additional 5 minutes. Cool on a rack. Reduce the oven temperature to 350 degrees F.
13. Remove the zest from the lemons with a vegetable peeler. Trim off any visible bitter pith with a sharp knife. Juice the lemons and reserve (you will have about 3/4 cup lemon juice)
14. Insert the metal chopping blade in the Cuisinart Food Processor. Place the lemon zest and 1/2 cup of the sugar in the work bowl and process until the zest is finely chopped, 1/2 minutes.
15. Add the remaining sugar, cornstarch and butter. Process until smooth, about 30 seconds.
16. Add the eggs, reserved lemon juice and vanilla. Process about 1 minute until well mixed.
17. Place the baked tart shell (still in the pan) on a baking sheet lined with foil.
18. Pour the lemon filling into the slightly cooled tart shell.
19. Bake in the preheated 350°F oven until golden brown and set, about 45 to 50 minutes. Allow the tart to cool on a wire rack at least 20 minutes before serving.
20. Garnish with fresh lemon slices or berries and serve with slightly sweetened or whipped cream if desired.