1 (14 ounce) can fat free sweetened condensed milk
1 cup reduced fat sour cream
1/3 cup plus 2 tablespoons lime juice
5 drops green food coloring, optional
1 (8 ounce) carton frozen reduced-fat whipping topping, thawed
1 (8-inch) reduced-fat graham cracker crust
Procedures : In a bowl, combine the milk, sour cream, lime juice, and food coloring if desired. fold in whipped topping. Pour into the crust. Refrigerate for at least 12 hours.