In a large saucepan, cook the onion, jalapeno if desired and garlic in oil until tender. Stir in the broth, beans, parsley, lime juice and cumin; bring to a boil. Reduce heat; cover and simmer for 10 minutes, stirring occasionally.
Combine cornstarch and water until smooth; stir into chili. Add chicken. Bring to a boil; cook and stir for 2 minutes or until thickened.