Vegetable Stock

Split the leeks lengthways and wash between the layers under the tap, opening each one out with your thumbs. Grit sits down in the middle of a leek, and nothing you do later takes it back out of the stock.

Cut the leeks, carrots and celery into rough 3cm lengths — small enough to give up what they have in forty minutes, large enough not to break down into the liquid.

Leave the onions in their skins. The papery brown layers are what tint the stock gold, and a pale stock looks like water once it is in the bowl.

Keep the brassicas out of the pot. Cabbage, cauliflower, broccoli, sprouts and all their trimmings turn sulphurous over a simmer, and even a small handful will dominate everything else in there.

Keep potato out as well. The starch it sheds clouds the stock, and it will neither settle nor strain out.

Warm the oil in a tall heavy pan over medium heat.

Add the leek, carrot, celery, onion and garlic and turn them through the oil.

Cover and sweat for 10 minutes, stirring once or twice, until the leeks have gone slack and the pan smells sweet, with no colour on anything.

Pour in the 2.5 litres of cold water.

Add the bay leaves, parsley, thyme and peppercorns.

Bring it up over about 10 minutes, to the point where the first lazy bubbles break the surface.

Adjust the heat until one bubble breaks somewhere on the surface every second or two, and no faster, so the liquid stays clear rather than churning cloudy.

Simmer uncovered for 40 minutes and no longer.

Hold to the forty minutes even though the chicken stock in this collection asks for three or four hours. There is no collagen here that needs the time: everything the vegetables have is out inside forty minutes, and past about an hour they start giving up bitterness instead — a dull, faintly cabbagey edge that no amount of reducing or seasoning covers up.

Do not salt it at any point, for the same reason the chicken stock is left unsalted. It exists to be reduced and seasoned in whatever it goes into.

Taste it at forty minutes. It should be sweet and clearly vegetal rather than tasting of warm water.

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

Press nothing against the mesh, which pushes softened pulp through and turns a clear stock cloudy.

Discard the vegetables, which have nothing left in them.

Divide the strained stock between two or three shallow containers rather than leaving two litres to stand 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.

Expect it to stay liquid in the fridge rather than setting to a soft jelly the way the chicken stock does. There is no gelatin in it to set, and nothing has gone wrong.

Keep it in the fridge for up to four days, or freeze it in portions for three months.

It makes about 2 litres: a pan of the minestrone in this collection with 500ml to spare, the sweetcorn chowder twice, or the roast tomato soup five times over.