Preheat oven to 375°.

In a bowl, mix graham cracker crumbs, sugar, and butter with you hands. Press mixture firmly into 9" pie pan and bake until brown, about 20 minutes. Remove from oven and allow to cool to room temperature before filling.

Lower oven temperature to 325°.

In a seperate bowl, combine sweetened condensed milk, lime juice, and eggs. Whisk until well blended and place the filling in cooled pie shell. Bake for 15 minutes and allow to chill in refrigerator for at least 2 hours.

Once chilled, combine sour cream and powdered sugar and spread over the top of pie.

Sprinkle with lime zest for garnish and serve chilled.