1. In a saucepan, combine butter, sugar, lime rind, and juice.
2. In a separate bowl, whisk eggs slightly, then set aside.
3. When mixture in saucepan just begins to boil, reduce heat.
4. Pour a ladle full of the hot mixture into the eggs, tempering them.
5. Then whisk all of the tempered egg mixture back into the saucepan.
6. Continue cooking, whisking or stirring constantly, until filling is thickened.
Tips: This filling can also be made with lemons; Simply substitute lemon juice
for lime juice and lemon rind for lime rind. This filling has approximately
a 5-day shelf life in the refrigerator. It cannot be frozen.
