Crush graham crackers into fine crumbs in food processor and combine with melted butter, 2 Tbsp sugar, 1 tsp vanilla, and salt in medium bowl. Stir until combined.
Use the bottom of a glass to press mixture into 9 inch glass pie plate. Bake 10-14 minutes, watching carefully to prevent browning.
Filling:
Zest limes and combine in large bowl with sour cream and sweetened condensed milk.
Slice limes in half and juice them using a garlic press. Add juice to bowl and whisk to combine.
Pour filling into slightly cooled crust and bake 5-8 minutes, or until tiny pinhole bubbles appear. Do not brown!!!!
Whipped Cream for Topping:
Combine cream, 2 Tbsp sugar, 1 tsp vanilla, and a dash of salt in a clean bowl. Mix on high speed until stiff peaks form. (I like mine almost overwhipped to the consistency of pastry cream)
Once pie has cooled, spread whipped cream on top and chill thoroughly.