Recipe by: TASTE OF HOME Chop one onion; set aside. Quarter the other two; place in a Dutch oven with chicken, water, celery, salt and pepper. Cover and simmer for 2 hours or until chicken is tender. Remove chicken; set aside. Discard celery and onion. To broth, add the tomatoes, carrots, bouillon and chopped onion. Cover and simmer for 30 minutes or until the carrots are tender. Debone and cube chicken; add to soup with zucchini and peas. Cover and simmer for 10 minutes or until zucchini is tender. Spoon into bowls. Garnish with avocado.