To begin with Heat a heavy bottom pan on medium heat. Slightly warm the puffed rice and keep it separately. Add jaggery and water to the pan and bring them to a boil, continuing to do so until the jaggery melts completely.
Once it is done, use a strainer to remove any coarse particles from the jaggery.

Next, pour the strained jaggery back into the pan and heat it on medium heat, bringing it to a boil.
Once the jaggery is thickened. To check the consistency, add a drop of jaggery mixture in a little water you will get a ball texture. Now you can add the puffed rice

Turn off the heat when done, and set aside for a few minutes to cool. 
Take a small portion of the mixture between oiled hands and shape it into a medium balls. Do this as soon as possible because the mixture will take it's shape and firm up when it cools down completely.

Finally, allow the Pori Urundai to dry a bit till it comes down to room temperature. Store the Pori Urundai or the Puffed Rice Balls in an airtight container.