1 tbsp gelatine
3 tbsp water
1/2 cup extra water
Sugar, to taste
4 egg whites
1. Squeeze the oranges and strain. Pour juice into a small bowl.
2. Mix gelatine and 3 tbsp water in a small, heatproof container and leave for a couple of minutes. Place the container in hot water and stir until dissolved. Combine with orange juice, extra water, and sugar.
3. Pour mixture into freezer trays or containers. Place into freezer until half-frozen.
4. Remove mixture from freezer and transfer into a mixing bowl. Beat well to break down ice crystals. Whisk egg whites until stiff, then fold into orange juice mixture. Return mixture to tray and cover it. Freeze until firm.
6. Using an ice cream scoop or a spoon, spoon sherbet into serving glasses. Garnish it with slices of orange if desired.