Prepare crust: Heat oven to 375 degrees. In 9 inch pie plate combine graham cracker crumbs and 2 tbsp. sugar; stir in butter until blended. Press mixture firmly and evenly over bottom and sides of pie plate; bake 10 minutes until browned.Cool completely on wire rack.
Prepare filling: In top of double boiler using wire whisk, beat egg yolks, lime juice, 1/3 cup sugar and salt until well blended. Set over simmering water. Cook about 5 minutes, stirring constantly until mixture is thick enough to coat back of metal spoon. Remove from heat. Stir in 1 tbsp. grated lime peel. Refrigerate mixture about 45 minutes until cool. Meanwhile, in large bowl with electric mixer at medium speed, beat cream until soft peaks form. Set 1 cup whipped cream aside for garnish. Fold cooled lime mixture into remaining cream. Spoon filling into prepared crust. Refrigerate at least 2 hours until set.
To serve: Spoon remaining whipped cream decoratively over top of pie; sprinkle cream with remaining 1 tbsp. lime peel. Garnish with lime slices, if desired.
Makes 8 servings.