What to do when you have too many mushrooms
A big haul of delicious mushrooms is thrilling! But what to do when you’ve eaten all that can decently be consumed, and you still have pounds left over? Mushrooms can go moldy in the fridge quite easily (and certain specific mushrooms, like inky caps and puffballs, can render themselves inedible in a day or so) so finding some way of preserving them is important.
One of the simplest and most reliable ways of preserving mushrooms is by drying them. Mushrooms should be sliced first, to quicken the process. If you don’t have a food dehydrator, you can put them on an aluminum foil tray over an electric lamp (or something else with a old-style light bulb you can just keep on) or the pilot light on the stove. My own stove has two hot spots from pilot lights that work very nicely; but my lights have all been switched over to fluorescent, so that doesn’t work for me anymore.
Mushrooms should be dried until they have the texture of a crisp potato chip. If they are still flexible, they will continue to rehydrate and… bad things will happen. This also means that they will need to be stored in air-tight containers. But if these steps are followed correctly, they will keep for years. Some museum herbaria still have dried mushroom specimens from the 1700s, though I’m not sure I’d want to eat them.
Some mushrooms get tough or otherwise get a bad texture when dried. Chanterelles get quite leathery, for example. These mushrooms can be dried and then powdered and added to dishes as a flavoring – or of course they can be preserved in other ways. Dried slices of giant puffball can be used to build a pizza on, or they can be crumbled into soup for a nice fungal flavor and thickening. Drying is the traditional way to preserve morels and boletes, and it strengthens their flavor.
Freezing is the other preservation method that comes naturally to most of us. The main point here is that all mushrooms should be sautéed (or parboiled, or briefly cooked in some other way) before being frozen. Otherwise, unless you really, really flash freeze (and unfreeze) them, they usually liquefy upon thawing – a most unpleasant experience. Oyster mushrooms are absolutely the worst for this, which is really strange since in nature oyster mushrooms can freeze solid on the tree, and you thaw them out and they’re fine. But if you freeze them in your freezer without sautéing first, you end up with mush when you thaw them.
This is also good for some mushrooms, like hen of the woods, that have a reputation for needing a long time to cook. In my experience, most of those mushrooms need some cooking at a higher heat than they often get in order to soften up. For instance, the hen of the woods one sees with a recommendation for soups or casseroles. But if you sauté it for a few minutes in a mixture of butter and oil, you can raise it to a temperature beyond what it usually reaches with those methods, and this softens it right up and you can just put it into your soup then and have it good to go. Or, likewise, you can freeze it then and have it cooked and ready to use as it comes out of the freezer. Also, you don’t have to sauté your mushrooms on their own – you can add some onions and garlic to the pan and make a mixture called duxelles that also freezes very well and is a great ready-to-use ingredient.
More elaborate preservation methods are of course possible: pickling, confiting, smoking are all good ways to make tasty preserved mushrooms. They also are more elaborate and take more work, and change the flavor of the mushroom more. With drying and freezing, you’re preserving the mushroom pretty much as much as possible with its original flavor. The two methods can be combined, to a certain extent: if you want to make absolutely sure of your dried mushrooms, you can put them in a deep freeze for a while each year (or microwave them) to kill any bug eggs or larvae that might be on them. Since your mushrooms are potato-chip crisp and completely dehydrated, they will not be affected by the microwaving (or freezing), right?
In any case, I hope this helps you enjoy your mushrooms.