Place the sugar in a saucepan with the water. Gently bring to the boil making sure the sugar is properly dissolved. Continue simmering until you reach a short thread. By this I mean, using a spoon, take some of the syrup out and test with your index finger and thumb. When you can see a short thread forming, the syrup is ready. This can take 15 minutes or more, so you will need to be patient. If you’ve gone from short thread to long thread, don’t worry. Just add a bit more hot water and try again.
Place the strawberries and lemon juice in a food processor. With the motor running add the syrup and keep whizzing until smooth. Taste and add more lemon juice if necessary. I like this sorbet quite tart, so you may need to adjust the sugar levels accordingly. Place in a metal tin and freeze until firm. If you are using an ice cream maker then follow the instructions for your machine.
To make the sorbet, place the frozen mixture in the clean food processor and whiz until smooth. Quickly place the mixture back into the tin and freeze until firm.