Zest 4 of the limes with a vegetable peeler or zester, being careful to avoid the white pith.
Place the zest and sugar in a food processor and pulse for 2 to 3 times. The zest should be very finely minced.
Squeeze the limes to make ½ cup of juice.
Cream the butter with the sugar and lime zest using a paddle attachment adding the eggs 1 at a time, and then add the lime juice and salt. Mix until combined.
Transfer the mixture into a 2-quart saucepan and cook over low heat, stirring constantly for ten minutes until thickened. The lime curd will thicken at about 175 degrees F, or just below a simmer. Remove from the heat and allow to cool for 1 hour.
Fill the Lime Tart Crust with the warm lime curd and allow to set in the fridge for three hours.
Make Whipped Cream and add to pie. Top with Maraschino Cherries and enjoy!