Liqueur Vinegar Pie

Directions

1. 1
   Preheat the oven to 350 degrees F.
2. 2
   In a heavy 2-quart saucepan, bring the water to a boil.
3. 3
   In a small bowl, combine the flour and sugar, tossing with a fork to blend.
4. 4
   Add the flour-sugar mixture to boiling water and cook, whisking often, until thickened, about 6 minutes.
5. 5
   Remove from heat and slowly add the eggs, whisking vigorously.
6. 6
   Return to medium-low heat and cook, whisking, until velvety smooth, about 3 minutes.
7. 7
   Add the vinegar and lemon extract and whisk just to blend.
8. 8
   Pour into the cooled pastry shell and refrigerate until set, about 3 hours.