This sorbet is quick and simple. The crushed blackberries on the top lend a tart finish that is most satisfying.
6 ripe nectarines
200g/7oz caster sugar
The juice of half a lemon
For the blackberries
2 tbsp icing sugar
The zest of one orange
Slice the nectarines in half, remove the stone and chop into one-inch pieces. Place in a blender with the sugar and lemon juice. Purée until smooth; it will have little specks of skin throughout, which is very pretty. Place in an ice-cream maker and follow the manufacturer's instructions.
If you don't own an ice-cream maker, freeze the mix in a low-sided container for two hours. Then remove and drag it with a fork, working from the outside in. Replace in the freezer. Repeat this every half hour three or four times, until all the mixture is formed of ice crystals. This makes a granita; its texture is slightly chewy, but it is just as delicious as any ice-cream.
Place the blackberries in a bowl with the icing sugar. Using the back of a fork, crush roughly; it should have a slightly coarse consistency. Stir in the orange zest and chill. To serve, spoon into chilled glasses and top with the blackberries.