Chicken Stock

Break the carcass into pieces small enough to sit below the water line, snapping the ribs and pulling the legs apart at the joints. This is what the roast chicken with lemon and thyme tells you to keep it for; thaw it first if it has been in the freezer since.

Put the carcass and the chicken wings into a tall, narrow pan. The wings are not optional padding — a single stripped carcass gives thin, watery stock, and it is the collagen in the wing joints that sets the finished stock to a jelly.

Pour over the 2.5 litres of cold water, which should cover everything by about 3cm.

Start from cold water rather than hot. Proteins that would seize on contact with hot water instead drift out and gather on the surface as the pan slowly warms, where a ladle can take them off.

Bring it up over about 20 minutes, to the point where the first lazy bubbles break the surface.

Skim the grey-brown foam off with a ladle as it gathers, and keep skimming for the first 10 minutes until the surface stays clear.

Drop in the onion, carrots, celery, bay leaves, thyme and peppercorns.

Adjust the heat until one bubble breaks somewhere on the surface every second or two, and no faster than that.

Never let it reach a rolling boil. A hard boil churns the rendering fat and the water together into an emulsion, and the stock goes cloudy, greasy and dull-tasting — and unlike almost everything else in cooking, this one cannot be undone. No amount of straining, chilling or skimming afterwards brings the clarity back.

Simmer uncovered, or with the lid propped ajar, for 3-4 hours, topping up with hot water if the bones ever break the surface.

Do not salt it at any point. Stock exists to be reduced and seasoned later, and salt added now concentrates along with everything else into something you cannot use.

Taste it after 3 hours. It should taste unmistakably of chicken rather than of warm water, and if it is still thin, give it another hour.

Set a sieve over a large bowl and ladle the stock through it.

Do not tip the pan out. The last of the liquid sits on a bed of sediment, and pouring drags all of it through the sieve and back into the clear stock you have spent four hours making.

Press nothing against the mesh. This is the opposite of the roast tomato soup, where forcing the pulp through is the whole point — there you want body, here you want clarity.

Discard the bones and vegetables, which have nothing left in them.

Divide the strained stock between two or three shallow containers rather than leaving the whole 2 litres in one deep bowl, where the middle of it stays warm for hours.

Stand the containers in a sink of cold water with ice in it, filled to just below their rims.

Stir the stock every few minutes and change the sink water once it has warmed through.

Aim to have it below 21C/70F within two hours of it coming off the heat, which is what the shallow containers and the ice are for.

Move it to the fridge at that point, where it should drop below 5C/41F within a further four hours.

Leave it uncovered until it is cold and cover it after that.

Lift the set disc of fat off the surface in one piece the next day and keep it for cooking.

Look at what is underneath. Good stock sets to a soft jelly that dents under a finger; if it is water-thin, the pan was too wide for the bones or the simmer ran too fast.

Keep it in the fridge for up to four days, or freeze it in portions for three months. It makes about 2 litres: one batch of the french onion soup, with enough left over for the roast tomato soup twice, or a pan of the minestrone with 500ml to spare.