What to do when you have three large white button mushrooms that have been in the fridge for two days? Still firm and white, but these mushrooms don’t have a long shelf life.
I mostly use these, sliced quite thin, once over lightly in a very hot skillet, sautéed in butter. Most people overcook mushrooms. Even Martha does. I can’t bear to watch her doing mushrooms.
So, like the parsimonious French, never wanting to waste, I decided to make soup. From only three mushrooms? Yes. The soup will keep for a few more days in the fridge. Keep the base in a covered container and you can feed four people, using only three mushrooms.
Start by saving deglaze from a skillet you have used to brown your steak. Add a couple of cups of water to that pan and bring to a roaring boil. Turn down the heat and simmer, scraping the bits stuck to the pan. If you don’t use this right away, store in the fridge for a few days, in a covered container. It comes in handy for many uses. It’s a great way to clean your pan and you can freeze the broth to use on another day.
After you have seared the mushroom slices (no salt) and sprinkled them with a bit of dried thyme (not too much; it’s very powerful and overtakes other flavours easily), add a couple of cups of your beef deglaze stock.
Peel two cloves of garlic. Add them whole. They will dissolve. Add a half peeled medium white onion to the pot. Peel and add a medium large potato cut in quarters.
Now add salt, the same way you would if boiling potatoes. Cover the pot and simmer until the potatoes are just done. Don’t let the liquid disappear. If you reduce it too much, just add a little water and bring it back to a simmer.
You can pop the covered pot, once cooled a little, into the fridge and save it until it’s ready to eat or you can purée it in your machine and then store. You have a great cream of mushroom soup base.
You can use the base immediately, but it is even tastier a day later. Store it in a covered fridge container.
To complete your rustic cream of mushroom soup, scald half-and-half cream. About a cup and a half should do. Let it rise and fall three times. The cream will thicken slightly. Then add the base to the hot thickened cream, stirring with a wooden spoon to combine. Do not boil.
It’s difficult to store after adding to the cream, so save that procedure until you know you are ready to serve. If the soup is for a special treat, serve it in a rustic open-face bowl, with a small dollop of sour cream with just the tiniest drizzle of real maple syrup, just when serving. You might like a couple of grinds of fresh black pepper on top.
A nice slice of crusty toasted open-face baguette swiped with a little garlic butter or herbed butter from my butter collection will make this a memorable soup for your guests.
Otherwise, perhaps serve it in an oversized cup. It’s great to keep on hand for sipping by the fire on a cold night.