Place the sugar in a pan with the water. Heat gently until the sugar has dissolved, then boil for 1 minute until the mixture is slightly syrupy. Pour into a bowl, add the lemon juice then cool.
Press the raspberries through a sieve, then pour the sugar syrup over the pips in the sieve to extract as much juice as possible. Pour the mixture into a shallow container and put in the freezer. After 2 hours take out and break up the ice crystals with a fork, then return to the freezer for another 2 hours.
Continue to break up the ice every hour until the mixture is firm. Move the container to the fridge 30 minutes before serving.
Use the same method to make bramley apple and elderflower sorbet. Simmer 600g (1lb 5oz) apples to a purée, blend and add to the sugar mixture with 3tbsp elderflower cordial. Freeze for 4½ hours
For an unusual twist, serve with basil sauce. Put two handfuls of basil leaves in a mortar with 1tbsp granulated sugar and crush with a pestle. Push through a sieve and drizzle over