Preparation: Separate thighs, legs and wings from chicken carcass, and chop them into bite-size pieces. Be sure to remove any bone splinters. Chop carcass into several pieces. Drain the mustard green; cut into 2" square pieces.
Soup: Put chicken and cold water in large pot. Bring to boil; skim froth and chicken fat; reduce heat to simmer. Simmer for 2 hours. Remove chicken carcass. Add mustard green; simmer another 15 minutes. Transfer soup with pieces and mustard green to serving bowl. Serve.
