1. Pie: In small bowl sprinkle gelatin over lime juice. Let stand until softened, 5 minutes. Stir to dissolve gelatin.
2. In large heat resistant bowl beat whole egg and yolk with electric mixer until thick and lemon colored, about 5 minutes. Add gelatin mixture and condensed milk. Beat on low speed just to mix.
3. In medium saucepan bring 2 cups water to simmer over medium-high heat. Place bowl with egg mixture over saucepan, making sure water does not touch bottom of bowl. Stir egg mixture over simmering water until heated through and thickened, about 10 minutes. Do not let egg mixture boil.
4. Remove bowl from over saucepan. Cool mixture in bowl. Refrigerate just until mixture begins to set. Beat again with mixer at high speed until light and creamy.
5. In small bowl, beat chilled evaporated skim milk with electric mixer until double in volume. Fold into gelatin mixture with lime zest, if using, until thoroughly combined.
6. Pour mixture into pie crust. Refrigerate until set.
7. Meringues: Preheat oven to 275 oF. Cover baking sheet with wax paper or parchment paper. In medium bowl beat egg white and salt until stiff peaks form. Beat in 3 tablespoons of the sugar gradually until very stiff. Fold in remaining tablespoon sugar and vanilla.
8. Spoon meringue mixture into a sealable plastic bag. Seal. Snip about 1 cm diagonally from one bottom corner. Squeeze bag gently over prepared baking sheet to force out small dollops of meringue, 2 cm in diameter. Make dollops until mixture is all used, about 10.
9. Bake meringues 40 minutes until dry to touch and lightly colored. With spatula, lift meringues from paper while still warm. Store in airtight container at room temperature or freeze tightly in sealed freezer bag. Use as desired.
10. To serve, arrange lime slices around pie. Top each lime slice with a meringue.
Crumb Pie Crust: In a small bowl or food processor, thoroughly mix 1 cup low-fat graham-cracker crumbs and quarter teaspoon ground cinnamon. Mix in 3 tablespoons softened light butter until well incorporated. Coat 23 cm pie plate with nonstick butter-flavored cooking spray. Press crumb mixture over bottom and up side of a plate. Bake in 375 oF oven for about 8 minutes or until firm and lightly colored.
Nutrient value per serving of pie: 218 calories, 6 g protein, 7 g fat (27% fat), 34 g carbohydrate, 175 mg sodium, 43 mg cholesterol.
Nutrient value per meringue: 4 calories, 0 g protein, 0 g fat, 1 g carbohydrate, 4 mg sodium, 0 mg cholesterol.