Add the cold water to a pan with the glucose and sugar.
Heat, stirring constantly with a hand whisk until the sugar is dissolved. Stop mixing and bring to the boil.
Remove from the heat, pour in the yuzu juice and zest.
Transfer to a plastic bowl, cover with cling film and allow to cool.
Once cool transfer to an ice cream maker and churn for 45 minutes until frozen.
Alternatively, pour the mixture into a strong plastic container and put in the freezer. After 1 hour 30 minutes it should have frozen round the edges. Take it out and beat vigorously with a fork, electric whisk or in a food processor until you have a uniformly textured mixture. Return it to the freezer and repeat at least twice more every 1 hour 30 minutes, then freeze for at least another hour.
Serve in parfait glasses with fresh raspberries or for a special treat cut the top off a fresh yuzu and scoop out the flesh. Fill the yuzu shell with the sorbet, pop the top back on and freeze.