How do I make a vegetable stock that actually tastes of something?

A meat stock gets its depth from gelatine and roasted bone. A vegetable stock has neither, so it needs its savour built in deliberately, and the usual failure is a pale sweet liquid tasting mainly of boiled carrot. Two changes fix nearly all of it: browning before the water goes in, and adding something rich in glutamate.

What you'll need

• Onion, carrot, celery, leek
• Oil
• Dried mushrooms (optional)
• Tomato purée or tomatoes (optional)
• Kombu seaweed or a parmesan rind (optional)
• Bay, thyme, parsley stalks, peppercorns (optional)

Step by step

1. Brown the vegetables in oil before any water goes near them.Roughly chopped onion, carrot, celery and leek in a hot pan with a tablespoon of oil, for ten to fifteen minutes, until there are dark caramelised patches on the base. This is where a vegetable stock gets its colour and most of its depth.
2. Add a tablespoon of tomato purée and cook it out for two minutes.It supplies glutamate, colour and a savoury sweetness. It should darken to brick red. Alternatively, a couple of halved tomatoes browned cut-side down do the same job.
3. Add a glutamate-rich ingredient.A small handful of dried mushrooms, or a strip of kombu, or a parmesan rind if the stock does not need to be vegan, or a tablespoon of miso stirred in at the end. This is the single largest improvement available and it is what separates a good vegetable stock from a boiled-vegetable one.
4. Cover with water by only a few centimetres.Vegetable stock is diluted far more often than it is under-extracted. Aim for a litre and a half of water to about a kilo of vegetables, not four litres.
5. Simmer for forty-five minutes, no longer.Unlike bones, vegetables give up everything they have quickly, and past about an hour they start giving up things you do not want — a dull, slightly bitter, cabbagey note, especially from brassicas and celery.
6. Strain without pressing, and season only if you will not reduce it.Pressing the vegetables pushes purée through and makes the stock cloudy and muddy. If the stock is destined for a sauce, leave it unsalted so it can be reduced.
7. Taste it on its own and correct it before you store it.It should taste savoury rather than sweet. If it is flat, add miso, soy or a spoonful of yeast extract. If it is too sweet, that is usually too much carrot — nothing removes it, so use less next time.

Tips

• Keep a bag in the freezer for onion skins, leek tops, celery leaves, mushroom stalks, parmesan rinds and herb stalks. Brown them straight from frozen when the bag is full.
• Avoid brassicas — cabbage, sprouts, broccoli, cauliflower — which turn sulphurous. Avoid potato, which clouds it. Go easy on carrot, which makes it sweet.
• Roasting the vegetables in a hot oven until the edges char, rather than browning them in a pan, gives an even deeper stock and needs no attention.
• A splash of white wine reduced in the pan after browning adds an acidity that makes the stock taste less flat.
• Dried mushroom soaking liquid, poured in carefully so the grit stays behind, is the strongest savoury liquid in an ordinary kitchen.

Common mistakes

• Simmering it for hours like a bone stock — Vegetables have nothing left to give after an hour and start releasing bitter and sulphurous compounds. Long cooking makes it worse.
• Drowning the vegetables in water — You cannot concentrate flavour that was never there. Less water gives a stronger stock in less time.
• Using only onion, carrot and celery — Those three give sweetness and aroma but no savour. Without a glutamate source the stock will always taste thin.

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