In a large saucepan, combine stock concentrate and hot water. Bring to the boil then turn off heat, leaving the pan on the element.
In another large saucepan, heat butter over medium heat. Add onion and cook, stirring often, until soft and translucent.
Add rice to pan and cook, stirring, for about 2 minutes or until rice is just starting to crackle. Add wine and Indian seasoning and cook, stirring, until absorbed.
Stir stock then add 1 ladleful (about ¾ cup) to rice mixture and cook, stirring, until absorbed. Repeat 1 ladleful at a time until all but 1 ladleful of stock has been added and absorbed by the rice.
Stir in prawns and most of the parmesan and chives (keep a little of both aside for serving).
Turn heat off, leaving the pan on the element. Cover pan with lid and leave to stand for 3 minutes (no peeking!).
Risotto must ooze over the plate—it should run almost like a soup—so if it's a bit thick, add as much of the remaining stock as necessary. Season to taste with salt and pepper.
Transfer to serving plates then sprinkle over remaining parmesan and chives and enjoy.