Chicken Soup with Avocado and Lime

1) In a large stockpot, combine chicken, celery, carrots, onions, garlic, salt, cumin, oregano, chilies, and 6 cups water. Bring slowly to a boil; cover and reduce heat and simmer until chicken is very tender. 2) ??? 3) To remove fat from broth, allow it to cool briefly; refrigerate broth several hours or overnight to allow fat to congeal on the surface. Remove and discard congealed fat. 4) Bring defatted broth to a boil; add green beans and cook, uncovered, for 5 minutes. 5) Add chicken; reduce heat and cook until heated through, 3 to 5 minutes. Taste and add salt if needed. Gently stir in tomatoes and cilantro. 6) Ladle soup into warmed bowls. Float 2 or 4 avocado slices and a slice of lime atop each portion. Serve at once.