Put the chicken carcass and vegetables into a large saucepan. Add the herbs, salt and peppercorns.
Pour over the water and bring slowly just to the boil. Skim off any scum with a slotted spoon. Reduce the heat to a gentle simmer, then half cover with a lid and cook for 2–2½ hours until reduced by about half.
Strain the stock through a large sieve into a jug. Remove any chicken pieces still on the carcass, pick out the meat pieces from the sieve and reserve for the soup, but discard the vegetables. Chill the stock for several hours or overnight Skim off the thin layer of fat on the top of the chilled and now jellied stock with a dessertspoon. Chill and store in the refrigerator for up to 3 days.
A duck, pheasant, or guinea fowl carcass or a ham knuckle can also be made into stock in just the same way. If you have a turkey carcass then double up the vegetable and water quantities specified above.
If you have a chicken carcass but don’t have time to make it into stock straightaway, you can freeze it for up to 3 months closely wrapped in clingfilm, then packed into a plastic bag. Defrost it at room temperature then make into stock as above.