Step by step
Cut 1kg nectarines in half, discarding stones.
Combine nectarines with a bruised, halved lemongrass stick, 280gm caster sugar, 80gm liquid glucose and 150ml water in a large saucepan (see note).
Bring nectarine mixture to a simmer over medium heat and simmer until fruit is softened
(5-10 minutes), then cool briefly.
Purée nectarine mixture in a blender, then pass through a fine sieve.
Churn purée in an ice-cream machine in batches, according to machine instructions, until a soft sorbet consistency, then transfer to a container and freeze until firm (1-2 hours). For the best results, churn sorbet around 2 hours before serving, so it’s ready to go in the freezer ahead of time. If it gets too firm, soften it in the refrigerator a little.
Why stop at nectarines? Apricots and peaches make great sorbet, too. Follow the same recipe as above, adjusting as follows: for apricot sorbet, use 300gm caster sugar, 85gm liquid glucose and 285ml water; for peach sorbet, peel the fruit and use 260gm caster sugar, 75gm liquid glucose and 95ml water.