Place chicken carcasses into a large stock pot add the water and bring to a simmer for 30 minutes. Cover the lid to allow partial escape of the steam either through holes already in your lid or by leaving the lid slightly displaced.
Turn off the heat and wait 5 minutes before skimming any scum, foam or froth that may have accumulated on the surface.
Add in all the rest of the ingredients, recover and simmer for about one hour, again with the pot covered to allow partial escape of steam.
Remove from the heat and allow to cool for 30 minutes before removing the solids with a slotted spoon or draining through a colander or large guage sieve into another container..
Use immediately or allow to cool to room temperature before transfering to freezerproof containers. I find 500ml to 1 pint containers a good size.
Video
How to Steam Sticky Rice in a Saucepan or Cheap Regular Steamer