Cornstarch Slurry
A Cornstarch Slurry is a simple mix of cornstarch and cold or warm liquid, whisked smooth and stirred into a sauce to thicken it fast. It’s the trick that turns a thin, watery gravy or soup into something glossy and rich without simmering it down for an hour. The standard ratio is 2 parts liquid to 1 part cornstarch, and it takes about 2 minutes to make.
Your sauce is thin. Dinner’s basically ready. And you’re standing there deciding whether to serve soup-adjacent gravy or let everything else get cold while you simmer it down.
Neither. Make a slurry.
Two ingredients, two minutes, and a thin sauce turns thick and glossy while everyone’s still at the table. It’s cornstarch whisked into liquid, poured into whatever you’re cooking, and that’s genuinely the whole technique. It’s the kind of thing that makes people think you know what you’re doing in a kitchen, which is honestly the best kind of trick.
It works on gravy, soups, stews, stir fry sauces, and fruit fillings like my Homemade Apple Pie Filling and Cherry Pie Filling. Once you know it, you’ll use it constantly and wonder how you got by before.
More Kitchen Basics
- Self Rising Cornmeal Mix – four ingredient homemade pantry staple
- Au Jus Gravy Mix – rich savory mix better than the packet
- Homemade Onion Soup Mix – skip the packet with this five minute blend
- DIY Hot Cocoa Mix – rich chocolate mix ready to scoop and stir
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See recipe card for complete information on ingredients and their quantities.
Ingredient Notes
Cornstarch – This is also called corn flour in some places. It’s silky and powdery, and it’s what does the thickening. Arrowroot powder or tapioca starch work as substitutes if that’s what you keep in your pantry.
Water – Easiest option, but broth or juice work too and add flavor while they’re at it. Some people insist on cold water. I use warm because it mixes smoother and I have never once regretted it.
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How To Make a Cornstarch Slurry
- Measure out your cornstarch and liquid using a 2:1 ratio, so 2 tablespoons of water to 1 tablespoon of cornstarch. Add the liquid to the cornstarch, not the other way around, which cuts down on lumps.
- Whisk until completely smooth. No lumps, no streaks. If a few sneak through, push it through a fine mesh sieve.
- Slowly pour the slurry into your hot sauce or soup while whisking constantly. Add it a little at a time so you don’t overshoot.
- Keep heating and whisking until it reaches the thickness you want.
For the full recipe and detailed instructions, please refer to the recipe card at the bottom of the post.
When To Add It
Add your slurry near the end of cooking. This matters more than people realize.
If you cook a cornstarch thickened sauce too long after adding the slurry, the cornstarch actually breaks down and your sauce goes loose again. So you’ll have done all that work to end up right back where you started, which is a genuinely annoying way to spend an evening.
Thicken it, get it where you want it, and get it off the heat.
Storage
Use It Fresh: Make a slurry right when you need it. It’s two minutes, so there’s no reason to prep it ahead.
If It Separates: Cornstarch settles fast, so if your slurry sits for even a few minutes, whisk it again before it goes in the pot.
Thickened Sauces: Sauces thickened with cornstarch can thin out slightly when reheated. Just make a fresh little slurry if you need to bring it back.
Don’t Freeze: Cornstarch thickened sauces can turn spongy or watery after freezing, so keep that in mind for anything you plan to stash.
Variations
Different Liquid: Use broth or juice instead of water to add flavor while you thicken.
Different Starch: Arrowroot powder or tapioca starch both work and are good gluten free options.
Equal Parts: Experienced cooks often use a 1:1 ratio instead of 2:1 for a more concentrated slurry. Start with 2:1 until you get a feel for it.
Fruit Fillings: Cornstarch is the go to thickener for pie fillings, giving you that glossy, sliceable texture.
Slurry vs. Roux: What’s the Difference?
Both thicken things, but they work at opposite ends of the recipe.
A roux is fat and flour cooked together in a pan at the beginning, before you add your liquid. You can brown it for deep color and nutty flavor, which is why it’s the right call for gumbo and classic gravy.
A slurry goes in at the end, as a finishing move when your sauce needs help right now. It’s faster, it doesn’t require planning ahead, and it keeps sauces clearer instead of opaque.
Neither is better. They’re just different tools. Roux when you’re building flavor from the start, slurry when you’re fixing a problem in the moment.
Frequently Asked Questions
It’s cornstarch whisked into a liquid, usually water or broth, then stirred into a hot sauce or soup to thicken it. The standard ratio is 2 parts liquid to 1 part cornstarch.
No, and please don’t. Dry cornstarch hitting hot liquid seizes into lumps immediately, and you’ll be fishing them out with a spoon. Mix it with liquid first, every time.
Either works. Some cooks swear by cold, but I find warm water mixes smoother and dissolves the cornstarch more easily.
It depends on the dish. Cornstarch works faster and keeps sauces clear and glossy. Flour takes longer to cook out and makes things opaque, but adds a bit more body.
You probably cooked it too long after adding the slurry. Cornstarch breaks down with extended heat, so add it near the end and pull the sauce once it’s where you want it.
Strain it through a fine mesh sieve before adding it to your dish. Better yet, whisk it until fully smooth before it ever goes near the pot.
Recipe Tips & Tricks
- Add the liquid to the cornstarch, not the reverse. Fewer lumps that way.
- Whisk until completely smooth before it goes anywhere near your sauce.
- Add the slurry gradually. You can always add more, but you can’t un-thicken a sauce.
- Whisk constantly while pouring it in so it distributes evenly instead of clumping.
- Add it at the end of cooking, not the beginning, or it’ll break down.
A cornstarch slurry recipe takes two minutes and saves dinner more often than you’d think. Keep this one in your back pocket and never serve a thin sauce again!
If you love this recipe as much as I do, please leave us a ⭐️⭐️⭐️⭐️⭐️ five-star review in the comment section below. Thanks!
Cornstarch Slurry Recipe
Ingredients
- 2 tablespoons water
- 1 tablespoon cornstarch
Instructions
- Whisk the water into the cornstarch.
- Continue whisking until smooth.
- Slowly pour the cornstarch slurry into your hot liquid or sauce that you are thickening.
- Whisk constantly until it reaches the desired consistency.
Notes
- Add the liquid to the cornstarch, not the reverse. Fewer lumps that way.
- Whisk until completely smooth before it goes anywhere near your sauce.
- Add the slurry gradually. You can always add more, but you can’t un-thicken a sauce.
- Whisk constantly while pouring it in so it distributes evenly instead of clumping.
- Add it at the end of cooking, not the beginning, or it’ll break down.
Nutrition
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