2 large grapefruit
2/3 cup sugar
3 T water
2 large egg whites
Remove rind and pith from grapefruit. Holding fruit over a bowl, cut between membranes, letting clean grapefruit sections fall into bowl. When all the sections are cut away, squeeze remaining pulp to release any extra juices. Pour grapefruit sections and juice into blender, blend for 10 seconds to chop up fruit. Set aside.
Combine sugar and water in small saucepan and place over low heat. Stir until sugar dissolves, then raise heat and boil for 1 minute, then remove from heat. Lightly beat egg whites with wire whisk or electric beater until foamy, about 10 seconds. Slowly beat into hot sugar syrup. Continue to beat until meringue cools down slightly. Add grapefruit juice and pulp.
Cover and refrigerate until cold or overnight. Mixture may separate, leaving foam on top, but it will incorporate into sorbet when it freezes.
Stir chilled mixture, then freeze in one or two batches in ice cream mahcine according to manufacturer's instructions. When finished, the sorbet will be soft but ready to eat. For firmer sorbet, transfer to a freezer-safe container and freeze at least 2 hours.
from The Ultimate Ice Cream Book, by Bruce Weinstein