It's not often that I take issue, never mind offense, with something Kenji writes, but in an otherwise lovely post about how to roast fall vegetables, he says, "Let's face it: Raw mushrooms are bland." This, to my mind, is a little extreme. I think reasonable people can disagree about whether raw button mushrooms have a delicate flavor, one that may require a particularly nuanced palate to fully appreciate (I say this as a reformed but longtime smoker). I must confess: I love button mushrooms any which way. Raw? Yes. Undercooked? Sure. Slippery? Why not? I can even recall enjoying a slimy button or two.
And yet, I have no quarrel with the recipe, and the end product is excellent. These roasted mushrooms are anything but bland: Mushrooms hold on to a lot of water due to their spongelike nature, and diligently cooking off that water concentrates their earthy flavor. The absence of excess liquid also makes quick work of giving the final roasted mushroom nubbins uniformly browned exteriors, while they remain juicy on the inside. Which is to say, they come out as advertised, lacking all those qualities that have deterred legions of (finicky) eaters from enjoying flavorful fungi. Have you tried the recipe? No? Please do; you won't regret it.
If you're already familiar with it, be sure not to skip one of the most wonderful steps: pouring off and saving the liquid that the cut-up mushrooms exude in the oven. That liquid, drained in order to facilitate browning, is an unexpectedly delicious by-product of the roasting process, an elixir made from salt, pepper, olive oil, and what can only be described as "mushroom juice."
Use it much as you would soy sauce—it's perfect for drizzling over anything that might need a salty, umami punch. Given that it's the holiday season, given that these roasted mushrooms are so excellent, given that you've tried them and are now roasting whole bushels of mushrooms (if mushrooms do in fact come in bushels), and given that your family is clamoring for more, why not collect all that amber liquid in some appropriately large container and put it to use to boost the flavor in, say, this udon bowl or this easy vegan risotto?
In fact, mushroom liquid will work in anything that benefits from a dose of meaty flavor, from pan sauces to soups made with chicken stock or even an All-American Beef Stew. Just keep in mind that it is not meant to replace the cooking liquid; it's more condiment than anything else, with a condiment's sodium levels, so add it in moderation. You can always add more.
And, if you have a bunch of leftover roasted mushrooms, remember that they can be used in this orecchiette recipe—just be sure to use the liquid, too!