How to Make It
In a medium saucepan, combine the grapefruit flesh, peels, and juice with the sugar and water. Bring to a boil, then turn down the heat to low. Simmer for 5 minutes until the syrup starts turning slightly brown and is reduced to about 1 cup. Remove from the heat, let cool, and strain.
Compost the solids and store the syrup in the refrigerator for up to 15 days.