Fresh raspberry lemonade

Method

1. Put 175g caster sugar into a pan with 250ml cold water and heat gently until clear. Boil rapidly for 5 minutes, then set aside to cool.
2. Whizz together the raspberries, remaining caster sugar and the lemon zest until smooth. Mix the syrup and 200ml of the lemon juice into the raspberry purée and press the mixture through a fine sieve set over a bowl to remove all the seeds. Chill until needed.
3. Just before serving, mix with 1 litre chilled fizzy water. Serve over ice.