Americana Key Lime Pie

1 tbsp (1 envelope) unflavored gelatin
1/2 cup sugar
1/4 tsp salt
4 egg yolks
1/2 cup fresh lime juice
1/4 cup water
1 tbsp grated lime peel (reserve some for garnish)
Few drops green food coloring
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4 egg whites
1/2 cup sugar
1 cup heavy cream
1  9-inch baked pastry shell

Thoroughly mix gelatin, 1/2 cup sugar, 
and salt in saucepan.  Beat together
egg yolks, lime juice, and water; stir
into gelatin mixture.  Cook and stir 
over medium heat just until mixture 
comes to boiling.  Remove from heat; 
stir in grated peel.  Add food coloring
sparingly to tint pale green.

Chill; stirring occasionally, until the
mixture mounds slightly when dropped 
from a spoon.  Beat egg whites till 
soft peaks form; gradually add 1/2 cup
sugar, beating to stiff peaks.  Fold 
gelatin mixture into egg whites.  
Fold in whipped cream.  Pile into cooled
baked pie shell.  Chill until firm.
Spread with more whipped cream; edge with
grated lime peel.