Heat Dutch oven or large saucepan coated with cooking spray over medium-high heat until hot. Add onions; cook and stir until tender. Add broth, rice, tomatoes and juice, chicken and chilies. Reduce heat to low; cover and simmer 20 minutes. Stir in lime juice and salt.
Just before serving, pour into soup bowls; top with tortilla chips, tomato and avocado. Garnish with lime slices and cilantro.