Melt butter in a large saucepan over medium-high heat. Add onion; sauté 5 minutes or until tender. Stir in chicken and vegetables; cook 3 minutes or until thoroughly heated, stirring constantly.
While chicken mixture cooks, combine water, flour, and broth. Gradually stir broth mixture into chicken mixture. Stir in salt, pepper, and bay leaf; bring to a boil. Reduce heat, and simmer 3 minutes. Stir in tortilla strips, and cook 2 minutes or until tortilla strips soften. Remove from heat; stir in parsley. Discard bay leaf. Serve immediately.