In a medium saucepan, whisk together sugar, corstarch and salt.
Whisk in water until blended.
Bring to a boil over medium heat.
Cook, whisking constantly for 2 minutes.
Remove from heat. Add butter, lemon rind and lemon juice.
Cook over medium heat, whisking constantly for 1-2 minutes until slightly thickened.
Remove from heat. Stir in coconut.
Place saucepan in a large bowl of ice water for about 5 minutes, whisking often, until it is completely cool.