How to Cook Paddy Straw Mushrooms: Canned and Fresh

Canned straw mushrooms are already cooked. Drain them, rinse the brine off, blanch them for thirty seconds if they still taste tinny, and give them one to two minutes of heat at the end of the dish. Fresh ones need three to five minutes, a same-day deadline and room temperature, never a refrigerator.

Almost everyone cooking straw mushrooms outside the tropics is cooking a can, and the can changes the whole job. The canning process cooked what is inside the tin, so your pan only has to heat it through. If yours are fresh from a warm-country market, they usually go wrong in the fridge or after a day on the counter.

Two products under one name

One species, Volvariella volvacea, reaches kitchens in two states, and they have almost nothing in common at the stove.

The canned ones are already cooked. Most recipes leave that fact out, which explains why so many bowls end up with rubber in them.

Fresh ones are a tropical crop grown on rice straw and cotton waste, in countries warm enough to keep a bed above thirty degrees, which is the main demand of growing paddy straw mushrooms. Farmers harvest them as firm closed eggs, a stage at which almost no other cultivated mushroom reaches a shop. They also collapse in transit at the temperatures used to ship every other vegetable, so Western shops stock tins and not baskets. Import law and demand have little to do with it.

The name causes its own small confusion in shops. Straw mushroom, paddy straw mushroom and Chinese mushroom all mean this species, and a can may carry any of the three. Specialist shops occasionally sell them dried. Those need twenty minutes in hot water first, and they come back with more flavor than the canned version but never with the snap.

Peeled or unpeeled on the label

Two words appear on straw mushroom cans, and neither the tin nor the shelf label has ever explained them.

Unpeeled means the whole egg, still wrapped in the outer sack the mushroom grew inside. These are smooth ovals that hold their shape in liquid, the ones you have seen bobbing in a coconut soup. Peeled means the packer has taken that sack off, which uncovers a small cap on a short stem and makes the thing look like a mushroom and less like an egg.

Which can you buy, peeled or unpeeled, depends on the dish:

• Unpeeled for anything wet, because the sack holds the shape in a broth.
• Peeled for anything sauced, because there is more surface and no skin over it.
• Either one halved, when you want a cut face in a soup and a shape on the spoon.

Neither is better and neither costs more, so no can bothers to argue for one. Underneath the two words sits a size grading, and it affects the dish more than either. Small ones stay firm and large ones have more space inside, so a can of large unpeeled mushrooms goes soft in a broth sooner than a can of small ones. If a shop stocks only one kind, buy it, because the difference changes how they look on the spoon and the dish still works.

Getting the can taste out

The tinny taste that people blame on the mushroom comes from the brine. That brine is salt and citric acid, and it soaks into the outside of every mushroom over months on a shelf.

1. Open and drain

   Tip the whole tin into a colander and let the brine run off completely.

2. Rinse under cold water

   Half a minute of running water, moving them with your fingers, is enough for most cans.

3. Blanch for thirty seconds

   Boiling water, then straight back into the colander, for cans that still smell of the brine.

4. Dry them properly

   Use a tea towel or a spin in a salad spinner, because wet ones will not brown.

Only the third step is optional, and it is worth adding when a can has sat on the shelf a long time. Rinsing alone takes out the bulk of the brine in about thirty seconds.

The blanch is the step people skip, and it finishes the job. It costs half a minute and removes the last of the metallic edge that a rinse leaves behind, without cooking them further in any way you would notice. Drying afterwards is essential if the mushrooms are going into a dry pan, and a salad spinner does it faster than any amount of patting.

One number on the can is worth reading before you buy several. Net weight includes the brine, and the drained weight is usually a little over half of it, so a large-looking tin holds less than it appears to. The rinse cannot put anything back, though. Canning costs the mushroom some of its firmness and most of its aroma, so a fresh one tastes noticeably cleaner even after identical cooking.

How long do straw mushrooms need in the pan?

Two numbers cover almost every dish, and the one that applies depends entirely on whether the mushrooms came out of a tin.

1. Get the pan properly hot

   Wide and dry, over the highest heat the burner gives, before anything goes in.

2. Aromatics first

   Garlic, ginger or chili, thirty seconds, so the oil carries flavor before the mushrooms arrive.

3. Mushrooms in, drained and dry

   Spread them in one layer and move them by tossing the pan, so they meet the metal.

4. One to two minutes for canned

   Long enough to heat through and pick up color, and no longer.

5. Three to five for fresh

   When they finish cooking, they shrink slightly and turn from matte to glossy.

6. Sauce at the end

   Oyster sauce or soy off the heat, because liquid ends the browning.

The fourth and fifth steps hold the whole difference between the two products, and everything around them is identical. Canned straw mushrooms left in the pan for five minutes go from firm to squeaky to rubbery, and nothing brings them back from the third stage. Fresh ones behave more like an ordinary mushroom. Even so, they finish faster than a button, because the flesh is thin over a hollow interior.

Overcooking leaves a visible signature in both cases. They shrink, wrinkle, and let go of a thin gray liquid that dulls whatever sauce they sit in. Wet mushrooms in hot oil are the other thing to plan for. Drained tins still hold water in the hollow middle, and tipping one straight into a wok sets off a burst of spitting that a minute in a colander would have avoided.

Halved ones behave better than whole ones in a dry pan. Their cut face sits flat on the metal and browns, while a whole egg rolls and only ever touches at one point. In a mixed stir-fry they go in near the end, after the harder vegetables have had their time and before the sauce goes down.

When to add them to a soup or a hot pot

More straw mushrooms end up in soup than in a wok. Pots pose a different timing problem from pans, because the pot is already hot when they arrive.

The rule underneath all four rows is that the mushroom is never the thing the pot is waiting for. Everything else finishes, and then they go in. Only the third row runs on attention in place of a clock, because a hot pot never finishes.

Straw mushrooms added to the pot too early go wrong in three ways:

• They shrink to about two thirds and stop looking like the thing on the menu photograph.
• They give up liquid that turns a clear broth cloudy.
• They soften all the way through and lose the snap that was the reason for adding them.

Hot pots are the one case that needs managing, since the pot stays on. Adding a handful at a time keeps the last ones as good as the first, and tipping a whole tin in at once guarantees the opposite. Most households that eat them know the result. Someone finds the last four at the bottom of the pot half an hour later, and by then they have the texture of a pencil eraser.

Cleaning fresh ones

Fresh straw mushrooms can take a quick rinse. They grow in straw and compost, pickers take them by hand from a warm bed, and they arrive with bits of both stuck to the outside.

1. Brush off the loose material

   Most of the straw comes away dry with a thumb or a soft brush.

2. Rinse briefly under the tap

   Cold water, a few seconds each, working into the folds where grit collects.

3. Halve any that are larger than a walnut

   Lengthwise, through the cap and stem inside, which also lets you see the flesh.

4. Dry and cook the same day

   Dry them with a towel and take them straight to the pan, because they do not improve on the counter.

Where they end up makes the rinse harmless. Straw mushrooms mostly go into wet dishes, so a surface that carries a little moisture costs nothing. Grit hides in the folds of the outer sack and not under the gills, because at the egg stage the gills are still sealed inside.

Some of what a market sells will have opened already. The sack splits, a small gray cap pushes out on a short stem, and you have a normal-looking mushroom in place of an egg. Opened ones are perfectly good and often cheaper, but they cook faster and go soft sooner, so they belong in a stir-fry and not in a slow pot.

Halving them is worth doing even when they are small enough to leave whole. Inside, firm white flesh means a good mushroom, and brown, mushy flesh means it spent a night somewhere cold.

Can you keep fresh straw mushrooms in the fridge?

Every instinct says the fridge, yet it is the one place fresh straw mushrooms cannot go.

Postharvest research documents tissue breakdown at ordinary refrigerator temperature, unlike the slow ageing that cold produces in a button mushroom. One preservation study compared holding them at fifteen degrees against four and found the warmer temperature kept them longer. That reverses everything a home cook has learned about vegetables.

In practice, keep them at room temperature in a paper bag or an open basket, and cook them today. Markets that sell them fresh keep them in open baskets on a counter for the same reason. That looks careless to anyone raised on chilled produce aisles, but it is the correct handling for the species. If today is truly impossible, cook them now and refrigerate the cooked dish, which keeps perfectly well.

Do you have to cook straw mushrooms?

Fresh ones, yes, and the reason is specific to this species. No cuisine that uses fresh straw mushrooms eats them raw. They contain volvatoxin, a protein that laboratory studies describe as cardiotoxic and heat-labile, so cooking breaks it down.

Two minutes of real heat is the working minimum for fresh ones, and any of the methods above clears it comfortably. The canned exception comes up constantly, so it deserves a plain statement. Cold, rinsed, canned straw mushrooms are a normal salad ingredient across Southeast Asia, and they give you nothing to worry about. Canning does the job thoroughly, since manufacturers heat the tins well past boiling under pressure, which is more heat than any home pan applies.

The egg that has killed people

Buying a labeled cultivated product and collecting a wild specimen call for different identification decisions. Straw mushrooms reach the shop as closed white or gray eggs sitting in a sack at the base. Young death caps are also closed eggs sitting in a sack at the base, and so are young destroying angels.

That resemblance is one of the best documented patterns in mushroom poisoning. It repeats wherever people who grew up eating straw mushrooms meet Amanitas that do not grow at home.

Two of those four rows are useless on a closed egg, and that is exactly the problem. The ring and the gills only show themselves once the mushroom has opened, and the egg is the stage at which people pick a straw mushroom. Inside the first trap sits a second one. Familiarity with the shape makes the mistake possible, so the people most at risk have handled real straw mushrooms for years in a country where no deadly Amanita grows.

Buy them from a reliable source. Treat an unidentified wild egg-shaped mushroom in a sac as potentially dangerous until a competent identification establishes what it is.

What they taste like

Nobody buys a straw mushroom for its flavor, and saying so is no complaint.

The texture is the reason they hold a permanent place in Southeast Asian cooking. The outside is smooth and a little slippery, the inside gives way with a small snap, and nothing else in the aisle does both at once. In a stir-fry they compete with mushrooms that bring more flavor to the same hot pan, and they win on texture alone.

That smooth, snappy texture has a short list of homes in Southeast Asian cooking:

• Coconut and lemongrass soups, where the texture stands out against a soft broth.
• Clear broths and noodle bowls, where nothing else provides a snap.
• Hot pots, where they are added and eaten in the same minute.
• Fast brown stir-fries with oyster sauce and something green.

They do not belong in a dish built on mushroom flavor alone, since a cream sauce or a mushroom soup asks for something they do not have. Quantity is easy to misjudge, because they shrink less than most mushrooms. Drained, one tin serves two people generously as part of a mixed dish, which is more than the same weight of button mushrooms would. Used for what they do well, they are one of the easiest things in the aisle to get right, and a tin, a colander, a hot pan and about ninety seconds make up the whole method.