fill about a third to half of the saucepan with water and let it boil a bit (or boil the kettle then pour that in), add chicken, stock cube and salt and pepper to taste and let simmer on low to medium heat for about 10-15 minutes.
while the chicken is boiling away, chop up your celery and carrot then add when chicken is slightly cooked.
add about half a packet of risoni (250 grams), give it a stir, you may need to add more water, and simmer on low heat for about 20 minutes or so, keep checking it and giving it a stir. You may need to add extra water as the risoni really swells up when cooked.
the risoni gives this soup the oomph and makes it a meal it itself. You can add extra vegies such as broccoli or cauliflower, but i like it with just the celery and carrot.