Mile High Lime Pie

1 can (14 ounces) sweetened condensed milk 1 cup (8 ounces) sour cream 1/3 cup plus 2 tbsp. lime juice 5 drops green food coloring (optional) 1 carton (8 ounces) frozen whipped topping, thawed 1 graham cracker crust (8 inches)

In a bowl, combine the milk, sour cream, lime juice, and food coloring. Fold in whipped topping. Pour into the crust. Refrigerate for at least 12 hours.