Place a rack in the middle of the oven and preheat to 350 degrees.
In a mixing bowl, blend together graham cracker crumbs, sugar, and melted butter until thoroughly combined. Firmly press the mixture into the bottom and up the sides of an 8- or 9-inch pie plate, creating a solid and deliciously spiced crust.
Pre-bake the crust for 10 minutes, and then remove it to a wire cooling rack while you prepare the filling.
In a medium bowl, combine condensed milk, sour cream, lime juice, and lime rind. Mix well and pour into graham cracker crust.
Bake in preheated oven for 10-12 minutes, until set and tiny pinhole bubbles burst on the surface of pie. Be careful not to brown your pie. Remove from oven and chill pie thoroughly before serving. Garnish with lime slices and whipped cream if desired.
