How do you use dried porcini mushrooms?

A small bag of dried porcini looks expensive for what it is, until you realise how far it goes. A modest handful changes the character of a whole pot: risotto turns woodsy, a tomato sauce gains a deep, savoury base note, a bowl of fresh mushrooms suddenly tastes more like mushrooms. Think of dried porcini less as a vegetable and more as a seasoning with a forest in it.

Soaking

Put the porcini in a bowl and cover them with warm water from the kettle, not boiling. Leave them until they are completely soft and pliable, with no stiff, leathery bits. Thin slices soften quickly; thick, chunky pieces take longer. Press them under the water now and then so they soak evenly.

Use only as much water as you need to cover them. Too much water dilutes the liquid you are about to treasure.

Some cooks soak in warm stock or even milk for particular dishes. Water is the most flexible choice, because you decide later where the liquid goes.

Saving and straining the liquid

This is the part people skip, and it is the best part. The soaking water turns dark brown and smells intensely of mushrooms. It is also, almost always, a little gritty: dried porcini bring some of the forest floor with them.

• Lift, don't pour. Scoop the mushrooms out with your hand or a slotted spoon, squeezing them gently over the bowl. The grit sinks to the bottom, so pouring would send it after them.
• Rinse the mushrooms quickly if you see any sand clinging to them.
• Strain the liquid through a fine sieve lined with a sheet of kitchen paper or a coffee filter. Leave the last spoonful, with its sediment, in the bowl.

Now you have two ingredients: soft porcini and a dark, clean, fragrant liquid.

Where a small amount does the most

Risotto

The classic. Chop the soaked porcini and soften them with the onion at the start. Add the strained liquid to your stock, warm, and ladle it in as usual. A mix of fresh and dried mushrooms gives you both texture and depth. Finish with butter and Parmesan. On the stirring question, see our risotto page.

Pasta sauces

Fry chopped porcini in butter or oil with garlic and parsley, add a splash of the liquid and let it reduce, then toss with tagliatelle and plenty of Parmesan. Or add both to a tomato sauce early on, where they lend a meaty, savoury depth without being obvious.

Soups and stews

Barley soup, bean stews, lentils, a winter vegetable soup: a little porcini and its liquid makes them taste as if they have been simmering all day. They also give a vegetable stock real backbone, which is half the battle with homemade stock.

Fresh mushrooms that taste of more

Fresh button or chestnut mushrooms can be a bit polite. Fry them until properly browned, then add a few chopped porcini and a splash of the liquid at the end. The ordinary mushrooms will taste wilder.

Porcini powder

Grind a few completely dry porcini in a spice grinder. A pinch of the powder seasons gravies, beans, roast potatoes or a butter for toast. It is one of the most useful tricks for savoury depth.

Buying and keeping

Look for large, pale slices with few crumbs at the bottom of the bag. The colour should be creamy to light brown; very dark, broken pieces tend to be older or lower grade. Keep the bag well sealed in a cool, dry cupboard. A jar works better than a rolled-up packet.