Preheat oven to 350 degrees.
Mix graham cracker crumbs, sugar and melted butter until well blended. Press mixture into an 8 or 9 inch pie plate. Set aside.
In a medium bowl, combine condensed milk, sour cream and lime juice. Mix well and pour into graham cracker crust.
Bake in preheated oven for 6 to 9 minutes, until tiny pinhole bubbles burst on the surface of pie. Make sure not to brown the pie by cooking for too long!
Add grated lime zest on top of pie. Chill thoroughly (about 45 minutes) before serving.
Garnish with whipped cream and lime slices. Enjoy!