Clean the soup greens and cut into small pieces. Peel and chop the onion. Put all ingredients - if you have meat or chicken broth, don`t forget the bones - in a saucepan with about 1.5 liters of cold water until everything is covered. Bring to a boil, then reduce the heat and simmer over low heat for about 2 hours. Skim off the resulting foam with a skimmer.
Pour the broth through a sieve or cloth and collect the liquid. Degrease the broth if necessary.