Crush cardamom in a mortar and pestle, then sieve to remove husks. Place ground cardamom, cinnamon, vanilla, lemon, butter, rice, milk, sultanas and 50g sugar in a 8cm-deep, 20cm-round microwave-safe dish. Microwave for 35 minutes on high, stirring every 5 minutes, until rice is tender and most of the liquid has been absorbed. Sprinkle with remaining sugar, place on the raised rack and cook on the grill setting for 10 minutes until golden.