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Quick Tip: How to Make and Use a Slurry to Thicken Soup

2009_01_05-Slurry.jpgMost of the time, we think of thickening soups and sauces with a roux, which is a mix of flour and fat added at toward the start of cooking. But a slurry added toward the end of cooking is another easy way to get a thicker, more luxurious sauce without a lot of fuss!

 
 

Think of a slurry as almost the opposite of a roux. A roux is cooked, uses fat, and is added at the beginning of cooking. In comparison, a slurry is uncooked, needs no fat, and is added at the end of cooking.

To make a slurry, just measure out the flour into a small bowl - use one tablespoon to thicken a small amount of sauce or up to four tablespoons for a big bowl of soup. Add a cup or so of the hot cooking broth to the flour and whisk until they're completely combined. This is your slurry.

Next, slowly pour the slurry into the main pot while whisking. This whole process prevents any lumps from forming and helps the slurry to incorporate evenly. Keep stirring the soup or sauce until it has thickened up.

In place of flour, you can also use corn starch, potato starch, or any other starch. If you already used a roux at the beginning of cooking but want to use a slurry to get an even thicker sauce, use a starch other than flour for the slurry.

Heads up: In culinary school, we were advised that using flour for both the roux and the slurry can cause hydrolysis, which is when the starch loses its ability to thicken. But more on that in a future food science post!

(Image: Emma Christensen for the Kitchn)

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Tips & Techniques, Ingredients - Pantry, how to, roux, slurry, starch, thickener

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Comments (7)

Back when I learned it a corn starch slurry needed to be ice cold and the dish you were thickening needed to be close to a boil to get the starch to activate properly. Have things changed?

posted by Ben L on January 5th 2009 at 2:27pm
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I find that as long as the corn starch is mixed with cold water and added to a hot liquid, you don't have to worry about the "tempering" step and don't get any lumps.

But be careful, thickening a soup with corn starch is what got Eugene in trouble in the Quick Fire Challenge on the Martha Stewart episode of Top Chef....

posted by joyosity on January 5th 2009 at 2:31pm
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Slurry...so that's what it's called. It's great to learn the real culinary terms (and the English terms) for techniques I watched my mom use while growing up.

posted by Michelle of Montreal on January 5th 2009 at 2:43pm
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Eww. I hate cornstarch. I can always taste it. If you don't want to use a roux, why not an egg yolk or cream?

posted by Palmetto on January 5th 2009 at 5:14pm
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I never had a word for this either, but it's what my mom always taught me to do to thicken stews and gravies.

posted by verily on January 5th 2009 at 6:40pm
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Arrowroot starch. No nasty cornstarch flavor.
http://www.penzeys.com/cgi-bin/penzeys/p-penzeysarrowroot.html?id=mRYICmwD
ta da!

posted by magdelane on January 5th 2009 at 11:43pm
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I use a canning jar and shake the tar out of it - no spatters and no lumps! I also use cold water and flour.

posted by luv2cook on January 6th 2009 at 5:42pm
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