Preheat your oven to 350°F (175°C). In a mixing bowl, combine ground pecans, graham cracker crumbs, melted unsalted butter, and powdered sugar until it resembles wet sand. Press firmly into a greased springform pan.

Bake for 10 minutes until slightly firm and set, then let it cool.

While the crust cools, zest and juice enough key limes to yield about 1 cup of juice. In a bowl, whisk together lime zest, lime juice, sweetened condensed milk, egg yolks, sour cream, vanilla extract, and sea salt until smooth.

Pour the creamy filling into the cooled crust and bake for 20-25 minutes until the edges are set but the center jiggles slightly.

After baking, let cool at room temperature for about 30 minutes. Cover loosely with plastic wrap and refrigerate for at least 4 hours or overnight.

Before serving, prepare a light whipped cream or meringue. Garnish with fresh lime zest or thin lime slices.