You can make a similar soup using leftover roast turkey or chicken. Remove as much of the meat from the bones; if you get more than two cups, you can divide it into portions so that you can make another dish apart from the soup. Then, take the carcass and simmer with herbs and aromatics to make broth. You will be able to make a generous amount of broth with a whole carcass. You can divide the broth into portions and freeze what you won't use to make this duck and white asparagus soup.