In a medium sized bowl, beat the egg yolks and lime zest together with an electric mixer on high speed until somewhat fluffy and well aerated, about 5 minutes.
Gradually add the condensed milk and continue to beat until the last of the condensed milk has been added and the mixture is rather thick and fluffy, about 4 minutes.
Slowly add the lime juice, mixing it on low until evenly blended.
Pour the filling into the chilled pie shell. Place the pie on the center oven rack and bake just until the filling appears set, about 10 minutes.
Transfer the pie to a wire rack and let cool thoroughly. Cover with loosely tented aluminum foil and refrigerate until very cold, at least 2 hours.