Wash and scrub the fruits. On a work surface, cut both ends of the fruit until the flesh. Make four incisions through the skin to the flesh. Gently pry the peel from the flesh and keep the flesh for another use. Cut the peel into strips.
In a heavy saucepan, cover the peel strips with cold water and bring to a boil. Drain and repeat three more times. The last time, simmer over medium heat for 15 minutes. Drain.
In the same pan, bring the water and 375 ml (1 ½ cups) of the sugar to a boil. Add the blanched grapefruit strips. Simmer for about 1 hour and until the syrup has thickened. Remove the strips from the syrup and place on a wire rack to drain well. Allow to dry on the rack for 24 hours.
Roll in the remaining sugar (125 ml / ½ cup). Store in an airtight container.
The candied peel will keep for several weeks in a cool and dry place.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.