From http://www.seriouseats.com/2014/10/how-to-make-simple-salad-worth-eating-vinaigrette.html
I’m a great cook but do not have a flair for making salad dressings unless I follow a recipe to the letter. But I’m a sucker for having a formula I can apply to tasks. When I discovered the secret to the perfect dressing is a simple formula, my pointy little ears perked up. I found this article by who writes: “The key to a perfect simple salad: knowing how to make a properly emulsified vinaigrette, applying just the right amount and washing and drying your greens thoroughly. Among the techniques that take you down the path towards a perfect simple salad are an emulsified vinaigrette, dressing-to-green ratio, clean and dry leaves, and 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. To form a stable, emulsified vinaigrette that stays blended 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.
PROPER TECHNIQUE (acid+mustard+aromatics and spices followed by oil)
The key to forming a strong emulsion is to start with your acid and mustard in a large bowl—you want something big enough to really get it moving. 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.
Whisking rapidly and over the entire bottom of the bowl, slowly drizzle in olive oil in a thin, steady stream. The reason you go slow is twofold. The first is so 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. 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.
PROPER RATIO: 3:1 oil to water-based liquid
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. A good ratio flavor and texture-wise is three-to-one oil to water-based liquid. For a particularly mild vinaigrette with a nice texture, I 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. 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. A blender doesn’t give the best result.)
WHY EMULSIFY? 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.
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
Start by washing your greens in cold water then spinning them dry in a salad spinner. 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.
Once they’re in the bowl, season them with a little pinch of salt and a few grinds of pepper. Drizzle them with a bit dressing, then start tossing. 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.
From http://www.seriouseats.com/2014/10/how-to-make-simple-salad-worth-eating-vinaigrette.html
THE RECIPE FOR A PERFECT SUPER SIMPLE VINAIGRETTE
A super-simple vinaigrette appropriate for all lightly dressed green salads.
Why this recipe works:
A 3-to-1 ratio of oil to vinegar makes for a perfectly smooth, thick emulsion.
Dijon mustard helps emulsify the oil and vinegar/water while shallots add mild sweetness.
Ingredients
1 small shallot, minced (about 2 tablespoons)
1 small clove garlic, minced (about 1/2 teaspoon)
2 teaspoons Dijon mustard
3 tablespoons white wine vinegar
1 tablespoon water
3/4 cup extra-virgin olive oil
Kosher salt and freshly ground black pepper
Combine shallot, garlic, mustard, vinegar, and water in a large bowl and whisk to combine. Whisking constantly, slowly drizzle in olive oil. Alternatively, place all ingredients in a tightly sealing jar, seal, and shake vigorously until emulsified. Season to taste with salt and pepper. Vinaigrette will keep in the refrigerator for up to 2 weeks.
About the Author
J. Kenji López-Alt is the Managing Culinary Director of Serious Eats, and author of the James Beard Award-nominated column The Food Lab, where he unravels the science of home cooking. A restaurant-trained chef and former Editor at Cook’s Illustrated magazine, he is the author of upcoming The Food Lab: Better Home Cooking Through Science, to be released by W. W. Norton.
From http://www.seriouseats.com/recipes/2014/10/simple-vinaigrette-recipe.html