Watermelon Sorbet

1 1/2 pounds watermelon, weighed without seeds or skin
1 1/4 cups granulated sugar
2 cinnamon sticks
2 tablespoons coriander seeds, crushed
3 tablespoons lemon juice

Reduce watermelon flesh to a puree.

In a heavy-based saucepan, dissolve sugar in 2 cups water. Add cinnamon sticks and coriander seeds and boil for 5 minutes. Cover and leave to infuse until cold.

Strain syrup into the watermelon puree and stir in lemon juice. Pour mixture into a container. Cover and freeze until firm, beating 3 times at 45-minute intervals.

About 30 minutes before serving, transfer the sorbet to the refrigerator.

Serves 8.