The Food Lab: How to Prepare Green Spring Produce

The Food Lab

Unraveling the mysteries of home cooking through science.

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Spring is the easiest time of year to cook. [Photographs: J. Kenji Lopez-Alt]

If quick and delicious are things you desire in the kitchen, then spring is the easiest time of year to cook. It's when all the sweet, crisp, fresh green versions of vegetables appear, vegetables so young and tender they barely need any heat. Sure, there are tons of ways to cook, say, asparagus, but the simplest and most versatile is blanching. Essentially a quick boil in a large pot of salted water, blanching can be a cooking method on its own, but it's also the gateway to other cooking methods, and a key technique to have in your spring cooking arsenal.

Most spring produce rapidly loses quality as soon as its picked. Asparagus and peas lose sugar and turn starchy. Fiddleheads start to decompose. Blanching freezes vegetables in their tracks, helping them retain their flavor and color. Whether you eat them as-is or use the blanched vegetables in another recipe (like this spring vegetable salad or this spring vegetable risotto), it's a technique that every good cook should have under their belt.

This guide will cover the basics of blanching as well as how to get a variety of spring vegetables ready or the pot.

You can read the whole thing or jump straight to a section with the navigation below.

Why Blanch?

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First, blanching will destroy enough cellular structure to just barely tenderize your vegetable to the point that it has lost its raw, fibrous edge, but still retains crunch. Second, intercellular gasses will expand and escape from the vegetable. This initial escape of gas is what causes the color of a vegetable to change from pale green to a vibrant, bright green—the gas pockets that had been diffusing light suddenly disappear, allowing the full color of the chlorophyll pigment to stand out. Meanwhile, enzymes that break down these pigments are deactivated by the high heat. That's why blanched vegetables appear brighter green—and more importantly stay bright green—much longer than fresh vegetables.

Of course, continue cooking too long and the chlorophyll will eventually break down and your vegetables will go from bright green to a drab olive green or even brown. But we'd never let that happen, right? Careful boiling, then shocking the vegetables in ice-cold water afterward, will stop the cooking in its tracks.

Once vegetables are blanched, they will last for several days in the refrigerator without any loss of flavor or sweetness. This is good news for delicately sweet vegetables like peas or asparagus that can turn bland and starchy when stored for more than a day or two. Blanched vegetables also go from fridge to dinner in a snap. Eat them cold with a vinaigrette, heat them up in a skillet with a little butter, add them to your roasted chicken, or even microwave them.

The Three Rules of Blanching

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There are only a few basic rules to blanching. Follow them and you'll be rewarded with tender-crisp vegetables with the brightest flavors and colors. This method will work for many of spring's finest green vegetables, including but not limited to: peas, fava beans, asparagus, fiddlehead ferns, snow peas, and snap peas.

Rule #1: Blanch the Vegetables in Water at a Rolling Boil. The goal of blanching is to get those color and texture changes to occur very rapidly without allowing time for the chlorophyll to begin breaking down. Contrary to popular belief, though, you don't need a big pot of water to accomplish this: As Daniel demonstrated in his blanching tests last year, smaller pots of boiling water will recover the boil just as fast, if not faster, than larger ones (and even though they may experience a bigger initial drop in temperature, it doesn't seem to have a noticeable impact on how the blanched vegetables come out).

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Rule #2: Blanch Vegetables Separately. Asparagus isn't exactly like a snap pea. Snow peas are thinner than fiddleheads. Vegetables all take a slightly different amount of time to cook depending on their size, density, etc. The only way to get all of your vegetables cooked perfectly is to cook them separately (you can use the same pot and same water, of course).

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Rule #3: Shock Your Vegetables in Ice Water. This rule was a no brainer for any chef a few years ago, then suddenly it became controversial because of a big, fat book that came out which reported that the hallowed technique was, in fact, useless.

That book got a lot of things right, but this is not one of them, and it's quite simple to prove to yourself: Blanch a big ol' pile of peas, take them out, and put them into a bowl without shocking them in ice water. Let them cool like that. What you'll find is that the peas at the bottom and center of the pile will have overcooked by the time you dig 'em back up.

This is because the reactions that cause a pea to lose its bright green color are not instantaneous. The peas have to be above a certain temperature for a certain amount of time to lose color. A single pea cooling at room temperature will rapidly cool to a safe zone. A single pea in the middle of a pile of other really hot peas, however, may stay hot for a good 15 minutes to half an hour, depending on the size of your pile. That's plenty of time for the pea to lose its color.

Moral of the story: if you are ever blanching more than one pea at a time, you should shock it in an ice bath afterwards.

Temperature and Timing

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When blanching vegetables, do not rely on a timer and do not rely on past experience. Trust nothing and no one save your own eyes and mouth. Despite the best efforts of Monsanto, vegetables are still real, living organisms that are naturally diverse. The asparagus you're cooking today is different from the asparagus you cooked last week. Watch carefully as they cook, fish out pieces and taste them often, and remove them as soon as they are ready.

That said, here's a rough guide to what you should expect. Use a timer at your own risk.

Vegetable Timing
Fava Beans 1 minute (shell before blanching, but remove skins after blanching)
English Peas 1 1/2 minutes (shell before blanching)
Garbanzo Beans 1 1/2 minutes (shell before blanching, but remove skins after blanching)
Fiddleheads 1 minute
Snap Peas 1 1/2 minutes
Asparagus (thin) 1 minute
Asparagus (thick) 1 1/2 minutes

How to Prepare Fava Beans for Blanching

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Fava beans have two separate shells you have to remove. The first is the thick, fibrous outer pod. To remove it, start by grabbing one of the ends, breaking it off, and pulling down on the strings that run along either side of the pod.

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It should easily come off in one piece.

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Using your thumbs, pry open the pod lengthwise to reveal the beans inside before popping them out.

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Fava beans have a thick skin around the individual beans even after popping them out of the shell, and they should be blanched before removing that skin. This is the one exception to the "taste as you go" rule, but about a minute is all you need before shocking in ice water and removing that skin.

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I'd always been told that you remove the skin after blanching because it's simply easier to do and results in fewer broken beans, but I wanted to try it both ways side by side. As it turns out, there's another reason to blanch in the skin: the beans come out with a much more intense green color and better flavor. Take a look at the photo above and tell me which bean you'd rather eat, the peeled-before-blanching bean on the left, or the peeled-after-blanching bean on the right. Easy choice.

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Fava beans also have a large pale nub called the radicle that can be removed by prying it off if you want extra points for presentation.

How to Prepare English Peas for Blanching

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Like fava beans, English pea pods are opened by first breaking off the end and removing any strings along the edges that come with it.

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Pop the pods open to reveal the peas inside.

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Use your thumb to pop the peas out. In some of the fancy restaurants I worked at, we'd individually peel each pea after blanching just like fava beans. I find this to be completely unnecessary when there's not a chef cracking the whip behind my back. The tender skins are totally edible and tasty.

English peas should be blanched for around a minute and a half, though that figure can vary depending on how large they are or on how starchy vs. sweet they are (older starchier peas should be cooked a little longer).

How to Prepare Fresh Garbanzo Beans for Blanching

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Fresh garbanzo beans are harder to come by, but if you're lucky you'll find 'em. They have a mildly sweet flavor and a texture that's slightly starchier than English peas. They're also a bit more of a pain to prepare as they generally come just one or two to a pod.

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To get at them, pop open a pod and peel back the shell to reveal and remove the beans inside.

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Blanch the beans for a minute and a half, shock them in ice water, then remove the fuzzy outer skin from each individual bean. Isn't that fun?

How to Prepare Fiddleheads for Blanching

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Fiddleheads are the immature early-growth stages of a fern. They pop up around springtime before rapidly unfurling into full-fledged adulthood a few weeks later. Unlike other super-sweet spring produce, fiddleheads have an earthy, almost briny flavor to them and a tender crunch.

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To clean them, start by trimming off any wooden or frayed ends.

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Next, hold the fiddlehead flat in one hand and scrape off any browned or protruding frond bits along the edges.

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Properly trimmed fiddleheads should be clean and tight. Blanch them for a minute before shocking in ice water.

How to Prepare Snap Peas for Blanching

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Very young snap peas with the stems removed may require no preparation at all, but if they're at all fibrous or have a stem end still attached, clean them by breaking off the end and pulling downwards along its edge to remove the string before blanching for one and a half minutes and shocking.

How to Prepare Asparagus for Blanching

There's a lot to say about asparagus. So much, in fact, that I've written an entire article on the subject, but there are really only a couple things you need to know when blanching asparagus.

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First off, that old trick about "letting the stem naturally break off where it snaps?" It doesn't really work—depending on how you hold the asparagus, you can get it to break in any number of places.

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Better is to visually inspect the asparagus and use a knife to cut off the bottom where it starts to get woody. At this point, you can gild the lily by peeling the lower stem of the asparagus, but it's not really necessary if a lightly fibrous texture doesn't bug you.

Once the asparagus is trimmed and optionally peeled, blanch it until crisp-tender, about a minute for thin stalks or a minute and a half for thicker ones.