I ended last month's adventures in soup with a discussion and recipe for Creamy Chanterelle Mushroom Soup, one of the first "fancy" dishes I ever learned to cook, and still one of my favorites to this day. It's like a souped up (excuse the pun) version of the cream of mushroom soup we all love,* and, much to my chagrin, is strictly forbidden on a vegan diet due to the 7 tablespoons of butter it contains.
*you do all love cream of mushroom soup, don't you?
What's a 'shroom-loving vegan to do? Why, devise a 100% vegan cream of mushroom soup every bit as rich and satisfying as the real thing, of course.
The difficulty lies in getting a thick, emulsified, creamy texture without the aid of dairy, and it's not a simple one to crack. Because of butterfat's uniquely long fat chains, it's much easier to incorporate into a stable emulsion than vegetable-based oils. Try substituting olive oil straight up for the butter and your soup breaks, turning grainy and greasy instead of luscious and creamy.
See, oil and water don't like to mix. You can stir them up, but eventually the oil will coalesce and break out into larger droplets. The starch and wheat proteins provided by blending a slice of soaked bread into the soup acts as a physical emulsifier, thickening the liquid and preventing dispersed oil droplets from coming back together.
And there's an added bonus: dairy fat has a tendency to dull flavors. A soup made with bread and olive oil in place of cream or butter not only achieves the same creamy richness, but it actually has a more intense mushroom flavor. That's right: this is a vegan cream of mushroom soup that's better than the real thing. (It might actually have me re-thinking my chanterelle soup recipe as well.)
Here's how it's done (or jump to the recipe with the links at the top and bottom of this post).
Start by sweating out your aromatics. In this case, I'm using a blend of onions, leeks, and garlic, though shallots would work fine as well. the goal is to soften them as much as possible without browning them, which can give them a distracting sweetness.
Next, add the mushrooms. In this case I'm using a pound of sliced button mushrooms along with 8 ounces of shiitake, though any combination of fresh mushrooms will work. In the meantime, I set aside a half ounce of dried porcini mushrooms to soak in a quart and a half of Hearty Vegan Stock.
The mushrooms cook down until their liquid has evaporated and they begin to sizzle.
Next up: a dash of flour, to help thicken up the broth and get the emulsion going.
In goes the sherry. As it reduces, it adds a layer of complexity, as well as some acidity to brighten up the finished bowl.
Once the sherry is reduced, I add a couple of my secret vegan weapons: soy sauce and miso paste. Both are extremely high in glutamates, which lend a savory backbone to the dish.
Now I add the soaked porcini along with the vegetable stock, a few sprigs of thyme, and a couple of bay leaves, letting the whole thing simmer for about half an hour to let flavors develop and the liquid slightly reduce.
In goes the bread to soak. It doesn't take long. And be wary: not all bread from the supermarket is vegan-friendly. Many shelf-stable sandwich breads contain milk solids or whey. Check your labels!
While the soup is simmering, time to make your garnish of crispy shiitake chips. Niki made some of these a few weeks back and used them in a garnish for a delicious kale salad that she made us for lunch, which got me thinking that they'd make for an excellent vegan staple whenever some crunch and intense flavor is needed.
You cook thinly-sliced mushrooms over very low heat in oil until they get nice and crisp around the edges and absorb some of that fat. I hate to make the comparison, but they're almost bacon-like in the way they crunch and release little bits of fat into your mouth as you eat them. (This makes me think of a new project: smoked shiitake chips.)
As soon as they get nice and brown, I drain them on paper towels and season immediately with salt.
When your soup has simmered away, it's time to blend. Just like making a mayonnaise, you want to emulsify your soup slowly so that your oil gets fully incorporated. Put the soup in the blender, bring it up to high speed gradually, then pour in a few more tablespoons of oil in a thin, steady stream. You should see the soup thicken up nicely as you do it. Season it with salt and pepper.
For the ultimate in luxury, press it through a chinois or fine mesh strainer to get it velvety smooth.
Here's a fun game: garnish the soup with those crispy mushrooms, some sliced scallions, and a drizzle of olive oil and serve it up to any non-vegan you know, and see if they make any comments other than how intensely mushroomy it is, how perfectly creamy it tastes, or just plain how darn delicious it tastes. I will wear this soup as a hat and post it in a public forum if they do!
About the author: J. Kenji Lopez-Alt is the Chief Creative Officer of Serious Eats where he likes to explore the science of home cooking in his weekly column The Food Lab. You can follow him at @thefoodlab on Twitter, or at The Food Lab on Facebook.