Add the caster sugar to a sauce pan along with 250 g of water.

Place the pan on a medium heat and bring to the boil, stirring occasionally until the sugar has all dissolved.

Add the batons of rhubarb to the boiling syrup, then immediately turn off the heat.

Place the pan to one side to cool for at least 15 minutes. The rhubarb will continue to cook and soften during this time.

Remove the rhubarb batons from the syrup.

Either serve immediately, or chill and keep in the fridge until required.