Pour the water in a thick-bottomed saucepan and add the rice. Bring to the boil and cook for about 2-3 minutes, stirring.
Turn down the heat to low and add the milk in one go. Cook for about 10 minutes, stirring frequently.
Add the vanilla pod to the pudding (if using icing sugar, wait until the end before you add).
Reduce the heat to a simmer, cover the pan and continue to cook for about 20 minutes, stirring occasionally as to ensure the rice does not stick to the bottom of the saucepan.
When the rice is cooked (keep tasting: You don't want overcooked rice) and the pudding is nice and creamy, add a spoonful of sugar as well as a good pinch of salt. Do not add the salt until the rice is cooked and the dish is almost ready.
You may find the rice pudding seems a little 'wet' - don't worry, it will thicken up as it cools and it will become a lot thicker. At any point, if you pudding starts to thicken too much, it means your rice are very starchy - just add more milk or water to thin it and continue cooking as instructed.
Serve with a knob of butter in the middle - and dust with cinnamon sugar (1 part cinnamon, 5 parts sugar).