How to Stop Your Homemade Salad Dressing from Separating

Once you learn the secrets to creating an emulsified dressing, you'll never go back to the old way.

There's nothing more maddening than watching a homemade vinaigrette separate, leaving guests to pour either all oil - or all vinegar - on their salads. It can be painful, but thankfully we have the solution.

It's all about emulsification: the key to making dressings that stay mixed for days – yes, days – in the refrigerator. All you need is a food processor, blender, or, in a pinch, stick blender, or basic hand whisk.

How Salad Dressing Works

When you look at a bottle of perfectly blended vinaigrette, you are seeing the results of emulsification. Technically, vinaigrette is a "water-in-oil" emulsification (vinegar, a "weak acid," contains 95 percent water). Oil and water do not mix, but clever chefs have figured out a way to make them combine.

In an emulsified mixture, the water base has microscopic droplets of oil suspended in it, and when properly made, the mixture will stay in suspension long enough to get through dinner.

Get the Recipe: Fresh Raspberry Balsamic Vinaigrette

The key to success is to incorporate emulsifying ingredients into your water base, so it will trap and hold the oil droplets. Add the oil in a slow, steady stream as you whisk or process it, so the stream of oil is broken into tiny droplets as soon as it enters the mix.

Fresh Raspberry Balsamic Vinaigrette

A Template for Dressings That Don't Separate

In this easy method, garlic and mustard are used as emulsifiers to help bind the surfaces of the water and oil in the dressing. Adding other ingredients like nuts, honey, mayonnaise, and tahini will also help emulsify the dressing.

Build Your Base

The best way to achieve a fully emulsified vinaigrette is to use a food processor.

With the machine running, drop in a garlic clove along with a small, peeled shallot or slice of onion. Add a few tablespoons of parsley or a pinch of fresh thyme, salt and pepper, a pinch of sugar or a drizzle of honey, and a spoonful of Dijon mustard.

If you prefer thicker dressings, add a couple of tablespoons of pecans or walnuts.

Process the mixture until relatively smooth, then drizzle in vinegar or lemon juice with the machine on. Scrape down the sides, and cover with the lid. With the machine running, slowly drizzle in the oil until combined.

The proper ratio for vinaigrette is 2 parts oil to 1 part vinegar. For a milder dressing, you can add more oil to your liking. Properly emulsified dressings will stay mixed for at least a day or two in the refrigerator.

How to Emulsify With a Blender
First, add the vinegar or lemon juice followed by the garlic, and onions, and blend until smooth. Then, run the machine at a slower speed as you drizzle in the oil.

How to Emulsify With an Immersion Blender
Use a large cup and follow the process for the blender. Pro tip: When you drizzle in the oil, tilt the cup so it can go directly into the spinning blades.

How to Emulsify With a Whisk
First, mince all the ingredients and place them in a medium bowl. Whisk in the vinegar or lemon juice. While continuing to whisk, slowly pour the oil into the tines of the whisk. You'll get an arm workout, but your dressing won't separate for a few hours.

Can You Emulsify With a Jar?

You may be wondering about the old-fashioned "shaking it in a jar" method. This works best when using a very thick base. Keep in mind you'll have to shake like crazy to break the oil into microdroplets.

Get the Recipe: Italian Dressing Mix

Once You Master the Method, Switch up the Flavors

Change up the base ingredients to give your dressing a different flavor. For example, try using rice vinegar, a shot of soy sauce, cilantro instead of parsley, and a slice of fresh ginger; blend in a neutral oil like canola or avocado. Or go for a Tex-Mex flavor profile by using lime juice, a pinch of chili powder, and cilantro instead of parsley.

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