1 small ripe rockmelon, peeled and seeded (you need 400 grams peeled weight)
¾ cup caster sugar
¾ cup water
3 tablespoons packed, fresh tarragon leaves
2 teaspoons grated fresh ginger
1 cup thick plain yoghurt
Put the sugar, water, tarragon and ginger in a small saucepan and bring to the boil, stirring to dissolve the sugar. Take off the heat and leave for 30 minutes to infuse. Strain the syrup and reserve the tarragon.
Roughly chop the rockmelon and place in a blender with the syrup. Blend until smooth then tip into a bowl.
Finely chop the tarragon and stir into the blended rockmelon along with the yoghurt. If you add the tarragon when blending, the sorbet goes a muddy colour.
Pour into a shallow metal freezer-proof container and freeze until frozen.
Chop the sorbet into rough chunks and in batches, place in a blender or food processor and process until smooth. Place back in the container, cover and freeze again. Makes about 4 cups