1 baked 9-inch pie shell
2 large eggs
1 c. sugar
1 tbsp. flour
1 c. cold water
2 tbsp. cider vinegar
cinnamon (for dusting)

Whisk together eggs and 1/4 cup of sugar until well blended. Whisk together remaining 3/4 cup sugar and flour in a 2-quart saucepan, then whisk in water and vinegar. Bring to the boil, whisking until sugar is dissolved. Add to egg mixture in a slow stream, whisking constantly with wooden spoon until filling coats back of spoon and registers 175°F on an instant-read thermometer, 12 to 15 minutes. Pour hot filling into pie shell and bake at 350°F for 15 to 20 minutes. Cool completely on rack and dust with cinnamon.

Makes 8 servings.