For caramelised mandarin compote, stir sugar and 100ml water in a saucepan over medium-high heat to dissolve sugar, then bring to the boil, brush down sides of pan with a wet pastry brush and cook until dark caramel (10-15 minutes). Reduce heat to low, add mandarin segments and juice (be careful as hot caramel will spit) and scraped vanilla pod and stir to combine. Cool to room temperature and refrigerate to develop flavours (overnight).
Bring rice and enough cold water to cover to the boil in a saucepan over high heat. Drain, return to pan with milk, cream, sugar, lemon rind, vanilla seeds and a pinch of salt, cover, then stir occasionally over low heat until rice is tender (30-40 minutes).
Bring caramelised mandarin compote to room temperature, divide warm rice pudding among bowls, spoon compote over and serve with extra compote.