Note: For the four weeks between January 14th and February 11th, I'm adopting a completely vegan lifestyle. Every weekday I'll be updating my progress with a diary entry and a recipe. For past posts, check here!
I mentioned the other day that when you give my wife free-reign to eat anything in the world, her top two choices are an arugula salad and butternut squash soup.
Here's the version I made for her this time.
Squash and carrots go very well together. They're both orange (duh), both have a great sweet-and-savory flavor profile, and both take well to conversion into creamy soup form. Just starchy enough to add some body and silkiness to the purée without being overly heavy.
You can make a perfectly serviceable squash/carrot soup by simply simmering the two together and pureeing the lot with some extra-virgin olive oil (or butter, if you prefer), but this being the middle of winter, I was after something a little deeper, a little more complex.
My first thought was to roast all the vegetables together. Roasting drives off some excess moisture, concentrating their flavor, as well as catalyzing the Maillard browning reaction, which adds color and complexity to the exterior of the roasting vegetables.
Then I thought to myself—what's the point of roasting a vegetable and concentrating its flavor only to water it down with plain old tap water when I subsequently want to puree it? What if, instead of roasting the carrots along with the squash, I were to juice the carrots raw and use that carrot juice as the liquid base for my soup?
I tried it out, adding a bunch of onions sauteed in olive oil until tender and sweet as well, heating the carrot juice (I juiced mine in a juicer, but you can just use bottled) just until hot so it retained most of its fresh flavor.
The soup was excellent—a nice salty/sweet contrast, a great combination of deep roasted aromas and bright, freshness. The final step was to emulsify it with some really good olive oil to add some body and texture to it. You can just whisk olive oil into the pureed soup, but you get a tighter emulsion and smoother texture if you drizzle in the olive oil slowly into the running blender, just like making a mayonnaise.
I figure this soup ought to put me in my wife's good graces at least until mid spring.
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About the author: J. Kenji Lopez-Alt is the Managing Editor 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.