2: Tip into a saucepan and add 250 g caster sugar. Leave the rhubarb and sugar to stand for 15 minutes to produce a syrupy juice in the bottom of the pan. Then cook the rhubarb over medium heat without a lid and stirring frequently. The aim is to cook the rhubarb without turning it to mush - the pieces should still be whole. Drain the rhubarb...
3: ...and keep the juice to one side. Preheat the oven to 210°C (410°F).