Creamy vegetable soups are one of those dishes that often seem like they should be more complicated than they are. Their final silky-smooth texture and layers of flavor suggest that lots of work has gone into them, but most of the time it's exactly the opposite. This fresh and herbal garlic scape soup is just another example of how little you need to put something delicious on the table.
It follows the general technique we've outlined for any creamy vegetable soup, with just one small deviation that I'll explain below. It starts with sweating leek and the garlic scapes in butter until tender but not browned—throughout this recipe, we want to develop flavor while preserving freshness, so each cooking step is meant to be just long enough to tenderize ingredients without any additional cooking. As soon as they've softened, in goes vegetable stock or water (you could use a basic white chicken stock too, if you don't mind the recipe not being vegetarian). I used water when developing this recipe and the results are still great, so it's not a problem if you don't have stock, but of course those additional layers of flavor are welcome if you have them.
Along with the stock, I decided to also add a single diced Yukon gold potato. This is to add body to the finished pureed soup while preserving lightness, which is something other possible thickening ingredients like cream or extra butter wouldn't accomplish as well. Pureeing cooked potato in a blender is often something we say to avoid, since it can create a gluey texture as the potato starch is released from its ruptured cells into the soup base, but when it's just a single potato in a couple quarts of liquid, the potato manages to thicken without those less desirable effects.
In our guide that lays out the basic technique for making any kind of creamy vegetable soup, we say to add aromatics to the pot as the ingredients all simmer together. In this case, the aromatics I'm reaching for are fresh mint and parsley, and I really don't want to lose their fresh, raw flavor, so instead of adding them to the pot to simmer, I do the opposite, cooling the simmered soup first, then adding the herbs to the blender so they can mix in without cooking. You can of course use whichever blender you happen to own for this, but this type of ulta-smooth pureed soup tends to come out best when you use a high-powered blender, such as a Vitamix, which are able to break down the herbs and other vegetables more thoroughly than most other blenders. It can mean the difference between a soup that's beige with little glittery flecks of herb floating in it and one that is totally homogenous and green, the herbs' chlorophyll fully released from the plant cells and no trace of a leaf to be seen.
The finished soup is minty and herbal, with a subdued garlic flavor, and while it's good hot or warm, my personal preference is to eat the soup at room temperature or even chilled. A dollop or drizzle of tangy dairy like sour cream or buttermilk is all it needs.
- 4 tablespoons (60g) unsalted butter
- One medium (8-ounce; 226g) leek, white and light green parts only, thoroughly washed of any sand or grit, then cut into large dice
- 1/2 pound (226g) garlic scapes (about 12 scapes), woody ends trimmed and scapes cut into roughly 1-inch lengths
- Kosher or sea salt
- 1 quart (946ml) vegetable stock or water, plus more as needed
- One medium Yukon gold potato (9 ounces; 255g), peeled and cut into 1/2-inch dice
- 1/3 cup loosely packed fresh mint leaves (about 30 leaves)
- 1/4 cup loosely packed flat-leaf parsley leaves and tender stems (1/2 ounce; 14g)
- Sour cream, crème fraîche, or buttermilk, for garnish
In a 3-quart saucier or saucepan, melt butter over medium heat until foaming. Add leek and garlic scapes and cook, stirring often, until softened but not browned, about 6 minutes.
Add vegetable stock (or water) along with the potato and bring to a simmer over medium-high heat. Cook at a simmer until potato is tender, about 5 minutes. Remove from heat and let cool until warm (to speed up cooling, you can set the pot in a larger mixing bowl filled with an ice bath).
Transfer broth and solids to a blender. Starting at the lowest speed and gradually increasing to high, blend until solids are thoroughly pureed and soup has a smooth texture. Turn off blender, add mint and parsley, then blend again until herbs are fully incorporated into soup. Return to saucier and whisk in additional stock or water until soup is pourable yet thick enough to lightly coat a spoon (about 1 to 2 additional cups). Season with salt.
Serve soup warmed, at room temperature, or chilled, garnishing with a dollop of sour cream, crème fraîche, or a generous drizzle of buttermilk.
The soup can be made up to 3 days in advance and kept chilled in the refrigerator. Serve chilled or rewarm, as desired.