FILLING:

1/2 c. grapefruit juice
1/2 c. water
1 c. sugar
3 tbsp. cornstarch
Red food coloring

Boil until thickened. Set aside to cool. Line baked pie shell with grapefruit sections. Cover grapefruit sections with filling and garnish with grapefruit sections. Option: Garnish with whipped cream. Chill.