1 clementine, juice only
800g/1lb 12oz rhubarb, trimmed and cut into 4cm/1½in lengths
500g/1lb 2oz caster sugar
80g/2¾oz cornflour
2 tsp vanilla extract
60g/2¼oz unsalted butter
600ml/20fl oz double cream
4 large egg yolks
900ml/1½ pints whole milk
200g/7oz kataifi pastry