The Food Lab's Asparagus Week, Day 1: Asparagus and Ramp Soup with Yogurt

I recently decided that I should try to be even nicer to my wife. She is, after all, the reason I married her. There are few vegetables my wife loves more than asparagus, and few things period that she loves more than soup. A good asparagus soup is worth at least a few dozen extra marriage points that I plan to redeem for goods and services at a future date.

All vegetables vary in quality and flavor with both the season and the distance traveled after harvesting (or more accurately, with the time between harvest and consumption). With some—say, carrots or zucchini—the change is not dramatic. I personally have a hard time telling the difference between a zuke grown in Mexico during the winter versus one that comes straight out of my own garden in the summer. Others, on the other hand, vary quite dramatically. Tomatoes. Corn. And yes, asparagus.

Now's the time of year that asparagus is at its absolute sweet and tender best around here, so I've decided to make a whole week out of it. Welcome to Asparagus Week! Each day this week you'll find a new asparagus recipe here that'll hopefully demonstrate the crazy versatility of spring's finest produce. (It'll also hopefully get my wife to be a bit more cheerful about waking up early to walk the dogs.)

The key to truly fantastic asparagus soup is the same as the key to truly fantastic grilled asparagus or braised asparagus or blanched asparagus or sauteed asparagus: start with truly fantastic asparagus. How do you do this? Well, start by heading to either a really good supermarket or grocery store, or better yet, your farmer's market.

See, asparagus fresh out of the ground is sweet and tender, but it very rapidly loses quality as its natural sugar convert into starches. That Peruvian asparagus you get in the mid-winter that's spent a few days on a refrigerated truck and a few more in a central distribution warehouse? That's only a pale imitation, a shadow of what real asparagus should be. Sure, it looks the way it should—tightly closed budding tips and firm, crisp stalks—but looks aren't everything.

When you buy your asparagus, do one of two things: talk to the person selling it to you to see where it came from (the right answer is "from the ground this morning"), or if there's nobody there, check the rubberband wrapped around the bundles, which indicates place of origin. If it says "Peru" or "Mexico" and you're shopping for your asparagus in May, leave it on the shelf and move along.

(Should you snap stalks or cut them? Does size matter? Does asparagus need to be peeled? How the heck do I store this giant grass anyway? For more tips on buying, storing, and cooking asparagus, see my guide from last year)

When you're making soup, it doesn't really matter if your stalks are thin and tender or thick and meaty—they're all going to get the same fate in the end anyway—so buy whatever looks the best. I like to keep my soup ultra simple and pure in flavor. I blanch my asparagus in a big pot of boiling water just until it's tender, then I puree it along with a big handful of sauteed ramps. In this case, I happened to have a bunch of ramps that my sister had sent me from her backyard in upstate New york (she very thoughtfully picked only the leaves, leaving the bulbs in the ground so that they could live to grow another season).

I could have simply blanched the ramps along with the asparagus, but I love the flavor of ramps sauteed in butter, and it adds an extra dimension to the finished soup.

I'm a butter fiend at heart, but I've recently been going through a serious extra-virgin olive oil phase, particularly the bright, grassy flavored ones. My current favorite is one pressed from Arbequina olives in Extremadura, Spain. It has a lightness and intense green aroma that screams spring to me and goes exceptionally well with the asparagus and ramps. (If you live in New York, you can get bottles of it at Fairway.)

As for the rest of the liquid, I like to use yogurt which adds both a touch of dairy richness, but more importantly some good acidity (which I supplement with some lemon juice).

Just like asparagus, this is a soup best eaten when it is first made. It'll have the brightest flavor and color within the first couple hours of blending. Indeed, leave it in the fridge overnight and you'll see a drastic change from bright emerald green to a drab olive.

It's the perfect start to a perfect week. Stay tuned for four more asparagus recipes over the next few days.