In a saucepan, combine chicken, onion, celery and parsley with cold water and chicken stock powder. Bring to a boil, reduce heat and simmer 20 minutes until soft.
When chicken is cooked, remove and shred with a fork. Strain the stock and discard the solids. Return the stock to the saucepan.
Heat the oil in a frypan over medium heat. Saute onion and garlic until transparent, about 3 minutes. Add tomatoes and cook 5 minutes. Let cool slightly then blend with 1 cup of the stock until smooth.
Add the tomato mixture to the saucepan with the chickpeas and carrots. Simmer 10 minutes. Stir in the shredded chicken and whole chillies and simmer 10 more minutes.
Serve, with grated cheese, avocados and lemon quarters on the side.