Directions

1. Use a vegetable peeler or large zester to remove 3 long strips of peel (just the zest, not the pith) from the grapefruits. Set aside. Squeeze out 2 cups of grapefruit juice.
2. In a saucepan, combine the grapefruit peel, sugar, corn syrup and water. Bring to a boil, stirring to dissolve the sugar, and cook for about 2 minutes. Set aside to cool. Place in the refrigerator, or set in a bowl of ice for faster chilling. Discard the peel.
3. Strain the grapefruit juice through a sieve or strainer to remove the pulp. Discard pulp. Stir the sugar syrup into the grapefruit juice, and mix in food coloring one drop at a time to achieve a pleasing, believable pink. (In other words, don't overdo it.)
4. Pour into the container of an ice cream maker, and freeze according to the manufacturer's instructions. Transfer to a container and freeze until firm before serving.