Soak gelatin in water.In double boiler over gently simmering water, beat yolks;add half cup sugar and lemon juice.Cook,stirring until mixture coats the bottom of a spoon.Add grated lemon peel,gelatin and food coloring.Stir well.Cool in refrigerator about half hour until slightly thickened.Beat egg whites with half cup sugar;fold into lemon mixture.Fold in whipped topping.Spoon into baked pie crust.Refrigerate 2 to 3 hours before serving.garnish with chocolate shavings and lemon slices.Serves 8.