The Food Lab Turbo: How to Make Vinaigrette (and Dress Your Salad Right)

The Food Lab

Unraveling the mysteries of home cooking through science.

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A perfectly dressed light green salad is really the only side dish you need in your arsenal. [Photographs: J. Kenji Lopez-Alt]

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I've had guests over a few times in the past week to taste test a cassoulet recipe I'm working on. It's an ultra-heavy French peasant dish made with beans and a ton of meat cooked down in the oven until incredibly rich. It's the kind of dish that pretty much demands a salad on the side.

What was odd to me was that twice in the past week, folks have commented on how tasty the salad was. Odd, because they were the simplest salads imaginable: bibb lettuce with the world's simplest vinaigrette dressing the greens. It occurred to me that the reason these salads seemed so tasty was that many people don't know what a simple salad should taste like. They've been so hammered by thick, gloppy bottled dressings or overdressed, soggy greens that they've forgotten what a pleasure a nice, light, side salad really is.

Good thing it's pretty easy once you know the basic steps.

There's only one key to a perfect simple salad: knowing how to make a properly emulsified vinaigrette, and applying just the right amount. Actually, there are two keys to a perfect salad: knowing how to make a properly emulsified vinaigrette, applying just the right amount, and washing and drying your greens thoroughly. Three keys... Let me start over.

Among the set of techniques that take you down the path towards a perfect simple salad are such diverse elements as an emulsified vinaigrette, dressing-to-green ratio, clean and dry leaves, and an almost fanatical devotion to proper tossing technique. Let's look at each of them.

Emulsion

Like mayonnaise, heavy cream, and most marriages, vinaigrettes are a just-barely-stable mixture of two things that really shouldn't get along under normal circumstances. In the case of a vinaigrette, those elements are oil and water. Yeah yeah yeah, that water comes in the form of an acid of some sort—whether it's citrus juice or vinegar—but for all intents and purposes, it behaves just like pure water around oil—i.e. it wants nothing to do with it.

You can combine water and oil and whisk 'em, shake 'em, or otherwise mechanically beat 'em as much as you'd like, but set them down on the table and let them sit a few minutes and inevitably the oil droplets will start to coalesce and float on top of the water forming two distinct layers.

To form a stable, emulsified vinaigrette that stays homogenous even after sitting around, you need to employ the aid of some chemical assistance. In the case of this simple vinaigrette, that assistance comes from Dijon mustard. See, mustard contains special molecules called emulsifiers. You can think of them as little Chinese finger traps with one side that only traps water molecules and another side that only traps oil.

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The key to forming a strong emulsion is to start with your acid and mustard in a relatively large bowl—you want something big enough to really get it moving.

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It helps to add your basic aromatic elements at this point—minced shallots and a tiny bit of garlic are what I'm using for this simplest of vinaigrettes—not only do they add flavor, but they also add turbulence, helping the whisk to do its job more efficiently.

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I stabilize my bowl by placing it on a folded up kitchen towel (you can make it even more stable by draping that towel over a pot and placing the bowl inside).

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Whisking rapidly and over the entire bottom of the bowl, slowly drizzle in olive oil in a thin, steady stream. The reason you want to go slow is twofold. The first is so that you are able to very rapidly break down large droplets of oil into smaller ones. The second reason is that large droplets of oil tend to attract smaller ones, helping them to escape from those finger traps. Add your oil too fast and the large pool of oil that ends up siting on top will prevent any more oil from being emulsified into the liquid underneath.

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Equally important to proper technique is proper ratio. As you add your oil, you'll notice that your vinaigrette starts out very thin. As you add more and more, it'll thicken up significantly until it reaches the point of maximum oil saturation. With the aid of a super-powerful blender, you can successfully emulsify oil into water at a ratio of over four-to-one. But it won't taste particularly good.*

*especially if you use extra virgin olive oil. Do NOT put extra-virgin olive oil in the blender—the rapid beating will cause it to rapidly oxidize, turning terribly bitter.

A much better ratio flavor and texture-wise is three-to-one oil to water-based liquid. For a particularly mild vinaigrette with a nice texture, I sometimes cut my vinegar or citrus juice in half and bulk it up with regular water.

As your vinaigrette starts to come together, you can add the oil a bit more rapidly.

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Once you've added the last drops of oil, you can taste your vinaigrette and season it with salt and pepper before giving it a final hard whisk. It should be thick and glossy, with just the slightest oily sheen to it. (P.S. if you want to skip on the whole whisking and measuring thing while making dispensing easier, just make it in a squeeze bottle.)

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So why emulsify anyway?

Well you can read the long version of the story here, but here's the quick and dirty.

It's like this: lettuces grow outdoors in places where it rains. In order to protect themselves, lettuce leaves have a thin, waxy, water-resistant coating on their surface. What this means for us in a culinary sense is that water-based liquids like vinegar or lemon juice run right off leaves, while oils tend to cling to them and cause them to soften and wilt.

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I'm sure you've all experienced this at those Italian restaurants with the oil and vinegar caddy at the table: a salad dressed in oil and vinegar very soon ends up as a pile of wiled greens in a pool of vinegary liquid at the bottom of the plate.

A properly emulsified vinaigrette, on the other hand, will allow that bright, vinegary flavor to cling to the leaves where it belongs.

How to Dress a Salad

As cute as Meg Ryan is in her dressing-on-the-side scene in When Harry Met Sally, Billy should have set her straight on something: dressing on the side is not a good option. Drizzling dressing on top of a plate of naked greens or, worse, dipping those greens into the tub of ranch on the side of the bowl leads to uneven dressing that masks the flavor of the greens instead of enhancing them.

A perfect simple salad should come pre-dressed with exactly the right amount of dressing gently napping every surface of every leaf. Just enough to brighten up its flavor while still letting the natural flavor of the lettuce—whether it's bitter, sweet, or peppery—to come through.

The world would be a much better place if we all just said no to dressing on the side.

For this to even begin to be possible, your leaves must be clean of any debris or dirt, and completely dry—any water on the surface of a leaf will prevent the dressing from adhering properly. Start by washing your greens in cold water then spinning them dry in a salad spinner.

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Next, place the greens in a bowl that you think is way too big for them. Seriously. I mean, WAY too big. The goal here is to give you space to toss those greens without fear that they're going to fall out all over the counter or floor.

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Once they're in the bowl, season them with a little pinch of salt and a few grinds of pepper—yes, even salads need to be seasoned properly (which may explain a lot of the bland salads I've had in the past).

Drizzle them with a bit dressing, then start tossing. Forget the tongs or those salad spoons and forks—none of them are gentle enough (and none of them will tell you whether your salad feels like it needs more dressing). Go ahead and get your (clean) hands in there, lifting the leaves from the bottom and letting them cascade gently through your fingers as you spread the dressing around.

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Once the greens are thoroughly coated, give them a taste and see if they might need a touch more salt and pepper, or perhaps a few more drops of vinaigrette.

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A simple salad is not the same as a boring salad. Properly dressed greens take just as much skill to prepare as, say, a good pan-seared steak (and come to think of it, this salad would be the perfect side dish for a good steak).

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Is it properly dressed now? Are you happy with it? Good—your guests will be too. Except for your cousin. Make sure you give her that side of ranch she wants or she'll be cranky all night.