Put the bones in a roasting tin and brown them in a hot oven.
Put the bones into a large saucepan with the vegetables, garlic and herbs. Do not add any salt. Almost fill the pan with water, bring to the boil and skim.
Boil gently but steadily for 2 to 4 hours. Skim frequently and add cold water when necessary to keep the bones covered. At the end of t