4egg yolks80 gmcaster sugar1 litre(4 cups) milk1vanilla bean, split and seeds scraped20 gmbutter300 gm(1½ cups) carnaroli rice40 mldessert wineTo serve:natural yoghurt (optional)Poached rhubarb220 gmcaster sugar2mandarins, juice only1lemon, thinly peeled rind and juice only200 gmrhubarb stalks (about 1/3 bunch), halved widthways, thinly sliced lengthways on a mandolin
For poached rhubarb, combine sugar, juices, peel and 250ml water in a saucepan over medium heat, stir until sugar dissolves, increase heat to high, bring to the boil. Reduce heat to low, simmer to infuse (6-8 minutes), add rhubarb, cook until tender (1 minute). Remove from heat, set aside.
Meanwhile, whisk yolks and sugar in a bowl until thick and pale (3-4 minutes), set aside until required. Combine milk, vanilla bean and seeds in a large saucepan, bring just to the boil, remove from heat, remove vanilla bean and keep warm.
Melt butter in a separate saucepan over medium heat, add rice, stir to coat and toast (1-2 minutes). Add wine and stir continuously until wine evaporates (1-2 minutes). Add hot milk mixture, 250ml at a time, stirring continuously until milk is absorbed before adding more. When rice is al dente (25-30 minutes), stir in egg yolk mixture and cook until thick (1-2 minutes). Remove from heat, divide among bowls, spoon over rhubarb and serve immediately with natural yoghurt, if desired.