Saute tomatoes, onion, and garlic in the bottom of a large soup pot till very soft. Add broth, vegetables, and spices.
Sprinkle chicken with lemon pepper and brown all sides in a small amount of oil in a medium hot skillet. Add the chicken to the soup. Simmer till veggies are tender and chicken is cooked through.
Remove chicken; shred, and return to soup. Heat through, and add salt and pepper to taste.