The Food Lab: All About Asparagus
If it ain't obvious to you already, I like meat. I deal with it a lot. It's tasty. I'm good at it.
But what you might not know is that I like vegetables even more. I mean, what would late summer be without Tomato-Mayonnaise-Toast sandwiches? How can you make a ramp omelet without the ramps? If L. and T. didn't exist, we'd have to content ourselves with plain old B.'s, and where's the fun in that?
And if ramps are the harbingers of spring, then asparagus is certainly its king. Amongst the vegetables that are available year-round from the supermarket, there are very few that show as drastic a change in flavor between the imported, year-round stuff, and the fresh-from-the-earth spring variety. Like peas and corn, asparagus contains a lot of sugar at the moment of harvest. As it sits around waiting to be cooked, this sugar quite rapidly begins to form starch molecules, turning a once tender and sweet stalk bland and starchy.
But the best part of asparagus is how darn easy it is to prepare. It's a great gateway vegetable for anyone who has been too intimidated to get into vegetable cookery (I know you're out there). There's almost no way short of incinerating or canning it to completely mess it up. And even if you do manage to mess it up, it's still pretty delicious stuff.
That said, there are a few questions about the powerful green stalks that need answering.
Whether you choose bright green stalks, mild white stalks (which are grown underground to prevent chlorophyll development), or any one of the purple varieties, you should always look for the same things: firm, crisp stalks with tight, fully closed budding tips. As the asparagus ages, the petals on the tip will slowly open up, dry out, or fall off. Asparagus should appear moist, but not wet. Fresh cut and bright, not dry or woody.
Your best bet for good asparagus is at a local farmers' market or direct from a farm. Unless your supermarkets are far far better than mine, the asparagus you get in them, even during peak season, have been out of the earth for far too long to really let their flavor shine. Unless it comes direct from the farmer, asparagus' point of origin is always written either on a label or rubberband affixed to the bunch. Do me, your farmer, and your tastebuds a favor: if you live in New England, don't buy the Peruvian asparagus in the middle of May.
Asparagus comes in all sizes, from slim, pencil-width stalks to big fat ones as thick as your thumb, and believe it or not, the size has nothing to do with their age (I would believe it). Asparagus stalks grow from an underground base from which scores of stalks shoot forth. It takes about three seasons for this crown to begin producing edible stalks, and after that, it'll continue to produce stalks for at least a couple of decades. It's the age and variety of this crown that determines the thickness of a stalk—that is, a farmer can't simply wait for a thin stalk to grow into a thicker one. It won't happen.
While both can be fantastic, I do generally choose one size over the other depending on how I'm going to cook it (or, more likely, I choose my cooking method based on the size of asparagus I happened to pick up from the farmers' market).
- Thin spears about 1/3 of an inch or less tend to be more intense in flavor and less watery. They're also a little bit tougher and snappier, due to their higher ratio of fibrous skin to softer interior. This makes them ideal for blanching, serving cold, stir-frying, or even just as a raw snack. Higher heat methods like broiling or grilling tend to dry them out a little too much, though if you like that charred asparagus flavor, you might still consider cooking them with these methods.
- Fat spears thicker than 1/3 of an inch are considerably more tender than small stalks, but can get a little watery if you steam or boil them. High heat cooking methods like grilling, broiling, stir-frying, and pan-searing are best, allowing you to get them nice and caramelized on their exterior while still maintaining a bit of bite. I awl use large spears for braising.
To Snap or to Slice?
Depending on its age, the bottom part of a stalk of asparagus can get unpleasantly woody or fibrous, and usually needs to be trimmed. But what's the best way to do this?
Traditional wisdom will tell you that the best "foolproof" way is to simply grasp the stalk at both ends and snap it. The asparagus will magically break exactly where it needs to. This question is often debated, and generally most people come down on the side of snapping. But is it really the best method, or merely an old wives' tale?
After some pretty extensive testing, I've come to realize that it's all a bunch of hokum. Indeed, depending on exactly how you apply force to the stalk, you can get it to snap pretty much anywhere along its length, even when your hands are in the exact same position. Check this out:
I snapped every one of these stalks with my bare hands, holding each of them at the exact same point, and was still able to make them break wherever I wanted to along their length—quite easily, I might add. For a method to be foolproof, it cannot be so strongly dependent on user input. How do I know I'm going to snap my stalks the same way my wife will? Or even if I snap stalks the same way day after day?
Far easier is to simply line them up, visually examine where most of the stalks appear to become woody (the stalk will begin to fade to white at that point), then slice them all at once, picking out any outliers and trimming them as necessary on a case-by-case basis.
Does this mean that you can't snap them? Of course not. There's more than one way to trim a stalk. Just know that you don't have to, and that most likely, you're not actually doing a better job of finding the "sweet spot" than you would do with a knife.
If you want to get extra fancy with your 'gus, you can peel the stalks in order to improve their texture. Even when properly trimmed, the outer layers can have a fibrousness that is apparently upsetting to the palates of people who do things like write Michelin guides.
For me, it's a skinless vs. skin-on hot dog thing. Sometimes I want that decisive snap and thin film-like layer that skin-on asparagus gives me, just like biting into a good Sabrett's. Other times, I'm content for tender, skinless franks. If you do decide to peel, don't throw them out! The peels are still plenty flavorful and can be used to make a creamy asparagus soup or in a vegetable stock.
The best way to store asparagus is to not. As I said, its flavor dramatically diminishes over time, so the sooner you get it in the pan and into your belly, the better.
If you absolutely must store asparagus, treat it like you would a bunch of flowers*. Place the trimmed ends into a cup of water with the stalks standing straight up, then loosely cover the tips with a plastic bag to prevent evaporation. Set the whole thing in the fridge.
Some people recommend adding salt or sugar to the water the stalks are held in, but I've never been able to detect any difference in flavor when you do this. Don't bother.
*Which it in fact isn't, despite what you may have read. Asparagus "flowers"—the part you eat—are actually modified stem structures. True asparagus flowers are six-tepaled (not to be confused with petaled, though they are, in fact, also six-petaled), bell-shaped affairs with poisonous red berries.
My Favorite Ways To Cook It
Asparagus is an extremely versatile vegetable and can be cooked in dozens of ways, though unlike, say, onions or spinach, it pretty much always takes center stage in whatever preparation you use it for. For a while, the fashion was to barely cook it so that the exterior was bright green while the interior was still essentially raw. Thankfully, we've passed that stage and have once again embraced asparagus in all its forms from raw and crunchy to braised, olive-green, and totally tender.
However you cook it, it almost always benefits from a period of hard, fast cooking which can then be followed (or not) by a slower-paced session to tenderize it. Like many vegetables, asparagus is high in sugar (even more so when it's completely fresh), and high heat takes advantage of this by caramelizing those sugars and adding a bit of complexity to the mix.
Here are my five favorite ways to eat asparagus.
- Raw, in Salads. If your stalks are slender enough, you're in luck. You can just chop them into segments and toss them directly into a salad dressed with a light, lemony vinaigrette, but if you've got big fat stalks, you've got to do a little more work (don't worry, the end result is worth it). Slice the stalks lengthwise using a vegetable peeler or a mandolin (be very careful if you do this) into strips about as thick as a piece of card stock. If you then store these in a bowl of iced water for about 30 minutes, they'll curl up into beautiful tangles that you can toss with other greens, or simply dress and eat on their own (or go the Jim Lahey route and top a pizza with it.)
- Blanched, Cold, with Lemony Mayo. Blanched or steamed asparagus is a great way to let its natural, delicate flavors come through, and it's what I usually do to very thin stalks. You can eat it hot, but I actually prefer it cold, dunking it in a bowl of ice water direct from the boiling pot as soon as its hit the tenderness level I'm looking for. When boiling asparagus, use a large amount of well-salted water at a rolling boil. The goal is to tenderize the stalk through to its center before naturally occurring enzymes have enough to time rob it of its bright green color. Unless you're going to serve your asparagus hot and immediately, shocking it in ice water right after cooking will prevent these same enzymes from continuing to work.
Despite what a certain 6-volume cookbook says, an ice water bath does indeed prevent blanched green vegetables from turning drab (try it out for yourself!)
- Grilled. Grilling some steaks and don't know what to serve on the side? Asparagus is a no-brainer. It cooks in the time that it takes for your steaks to rest, it's healthy, and it's dead simple to do. The high heat of a grill instantly starts caramelizing and charring asparagus' sugars while allowing the bulk of it to remain crisp and sweet. Smoky + sweet + crisp + easy = huge win for all backyard chefs. In order to make sure that they cook relatively easily and don't dry out on the grill, it's essential to toss them with a thin coating of oil before they hit the grates. Oil is not only a better heat-distribution medium that the naked air, it also keeps the stalks lubricated, filling in all the microscopic nooks and crannies left behind by evaporating moisture and preventing the 'gus from turning shriveled or leathery.
You can get fancy by drizzling melted herb butter, cheese, or lemon on them after cooking, but in all honestly, the best way to eat them is straight off the grill with your fingers. Get the recipe »
- Broiled or oven-roasted. Very similar to grilling, the key here is to use crazy high heat to maximize caramelization while still maintaining a pleasant crispness. The best way to do this is to use a relatively heavy rimmed baking sheet which you allow to preheat for at least 10 minutes or so in a 500°F oven on the bottom rack. Toss your asparagus with a bit of olive oil, salt, and pepper, and throw it on the pan. If everything went right (and there should be no reason it didn't), the asparagus will sizzle and start browning as soon as it hits the pan. Alternatively, place the stalks on a rimmed baking sheet a few inches away from a broiler element heated to high. A few minutes in the oven, and you're good to go. Sprinkle with some lemon or a nice sharp grating cheese. Parm works, Pecorino is better, Cotija is just plain cool. Get the recipe »
- Braised. This is my absolute favorite way to prepare it, and the one that was looked down upon for so many years. Why would you want to eat drab green vegetables?, people would say. Because they taste as awesome as MacGyver was cool, that's why. I sear my stalks in a bit of oil first to develop flavor, then deglaze the pan with either water or stock, add a big knob of butter, put a lid on the whole thing, and let the asparagus cook in the liquid as it reduced. By the time the stalks are tender, with good luck, your stock and butter will have emulsified into a slick, stalk-coating sauce that adds richness and sweet flavor to each bite. It's awesome. Get the recipe »
One last thing that you probably notice after your asparagus has been done eaten: That haunting smell—haunting as in it comes back and surprises you long after you thought it was gone—is caused by S-methyl thioacrylate and S-methyl 3-(methylthio)thiopropionate, chemicals identified in 1975 at the University of California at San Diego. It's not known exactly why some people seem unable to digest it, but it is known that the degree of Post-Asparagus Stinky-Urine Disorder (PASUD) is related to your genealogy. Fewer than half of Britons suffer from it, while almost 100% of the French do.
I know which country I'd rather be in for sporting matches during asparagus season.