Mushrooms Are Not a Vegetable and They Do Not Cook Like One
A mushroom is mostly water held in a structure that does not collapse when the water leaves, which is why every piece of advice about crowding the pan works differently here than it does anywhere else.
Put mushrooms in a hot oiled pan and for the first several minutes nothing good happens. They go pale, they release a startling amount of liquid, and they sit in it, squeaking. Most people conclude the pan was too crowded, turn the heat up, and get grayer mushrooms.
They were not crowded. A mushroom is somewhere between eighty and ninety percent water, and that water is coming out no matter what size pan you use. The difference between gray mushrooms and brown ones is entirely what you do during the several minutes it takes to leave.
The cell walls are not cellulose
A plant holds itself up with cellulose, and its structure depends on water pressure inside the cells. Take the water out of a zucchini and it collapses.
A mushroom is a fungus, and its cell walls are chitin — the same family of material as an insect shell. It is far more heat-stable and it does not depend on internal pressure for structure.
Which is why a mushroom can lose almost all of its water and stay recognizably a mushroom, only smaller, denser and chewier. It is also why mushrooms do not really overcook in the way a vegetable does. There is no crisp-to-mush transition and no bad middle; there is undercooked, cooked, and increasingly concentrated.
The pan does not brown until the water is gone
This is the same 212 ceiling that governs every other browning problem, and mushrooms hit it harder than anything because they are carrying so much more water.
So the sequence is fixed and cannot be skipped. The mushrooms release their liquid. That liquid boils away, holding the pan near the boiling point the whole time. Only when it is gone does the surface temperature climb and browning start, and then it happens fast.
The practical consequence is that the first four to six minutes are not a failure in progress. They are the necessary first phase, and the only mistake available during them is losing your nerve.
The dry sauté is the better method and it looks wrong
Put the mushrooms in a dry pan over medium-high heat with no fat at all. They release their water, it evaporates, the mushrooms shrink and begin to squeak and then to brown. Only then add the fat, and the salt, and the aromatics.
This works better than the usual order for two reasons. Oil added at the start is absorbed by the porous mushroom during the wet phase, which is where the reputation for mushrooms drinking a cup of butter comes from — they are absorbing it while there is still room. And fat held at frying temperature for six minutes of steam is just degrading.
Add the butter at the end, when the mushrooms are already dense and browned and cannot take much on, and it stays on the outside where you can taste it.
Salt at the start or the end is a real choice
Salt pulls water out. Added early, it accelerates the wet phase, which gets you to browning faster but produces flatter, more uniformly cooked mushrooms and a lot of liquid at once.
Added late, the mushrooms release their water more slowly on their own, brown in a more uneven and interesting way, and keep more of their bite.
Neither is wrong. Early salt for a duxelles or anything that is going to be chopped and folded into something. Late salt when the mushrooms are meant to be an element you can see.
Do not wash them, and then do not worry about washing them
The old rule says brushing only, because mushrooms are sponges. They are porous, but they are also already mostly water, and a quick rinse adds a small fraction of a percent to that.
The honest version: a brief rinse and a thorough dry costs you almost nothing and is far better than cooking gritty mushrooms. What does matter is soaking, which waterlogs them, and putting them into the pan wet, which adds minutes to the wet phase you were already waiting out.
Dried mushrooms are the opposite problem and the bigger opportunity. The soaking liquid is the single most flavorful thing produced in most home kitchens — concentrated glutamate, strained to leave the grit behind, and better than stock in anything savory.
They are one of the two halves of savoriness
Mushrooms carry glutamate, and dried mushrooms carry a large amount of guanylate, one of the nucleotides that multiplies rather than adds when it meets glutamate from somewhere else.
Which is the mechanism behind combinations that seem like folk wisdom. Mushrooms with beef, mushrooms with tomato, mushrooms with parmesan, mushrooms with soy. Each pairs a nucleotide source with a glutamate source, and the result is louder than either.
A teaspoon of powdered dried mushroom — a spice grinder and a handful of dried porcini — is the cheapest savory lever available, and it disappears into anything.
Which mushroom, and what actually changes
Button, cremini, portobello are the same species at three ages. Older means less water, denser texture and more flavor, which is why cremini are worth the small premium over white buttons and why portobellos can be treated almost like meat.
Shiitake have tough stems that should go in the stock bag rather than the pan, and caps that hold their shape and carry a lot of flavor. Dried shiitake is the most useful dried mushroom to keep.
Oyster and maitake have irregular edges that crisp beautifully and a lower water content, so they brown faster. They are the ones to roast or to fry hard.
Chanterelles and morels hold a lot of water and want a hot dry pan and no crowding, because their flavor is delicate enough to be lost under aggressive browning.
Roasting is the easiest version of all of this
An oven does the wet phase without supervision. Cut them large, toss with oil and salt, spread on a sheet pan with room, and roast at 400°F or higher. The water leaves, the mushrooms shrink by half or more, and the edges go crisp.
Cut them larger than feels right, because they will shrink dramatically, and use a pan big enough that the released steam has somewhere to go. On a crowded tray they never get past the wet phase, which is the one case where crowding genuinely is the problem.
They keep badly and freeze well once cooked
Raw mushrooms go slimy in a sealed plastic container, because the humidity has nowhere to go. A paper bag in the refrigerator gives you nearly twice the life for no effort.
Cooked mushrooms, on the other hand, freeze remarkably well. Most of the water is already gone, which means there is far less of it left to form damaging ice crystals, and that is unusual among things worth freezing.
A large pan of mushrooms browned properly on a Sunday and frozen in portions is one of the highest-value things to have in a freezer, because the expensive part — the twelve minutes of waiting out the water — is already behind you.
Part of Recipes & Technique.
