Put all the ingredients, except the parsley, in a large pan and add 4 litres of cold water. Bring to a boil. As soon as the water starts to boil, turn the heat down low. Add the parsley, half cover with a lid and let the broth simmer slowly for about 6 hrs. Occasionally, skim off the foam and fat using a ladle. (You could also transfer the stock to a large slow cooker once you have brought it to a boil.)

Strain the broth through a colander or sieve into another container. Cool, then chill so the fat rises to the surface.

Remove the solidified fat with a slotted spoon. You don't have to throw it away, it can be used in cooking. To give the stock a stronger flavour, bring it back to the boil and reduce it until it is the strength you want.