How To Thicken Stew In Pressure Cooker
How to thicken stew in pressure cooker, explained by a reviewer who actually lives with the gear. No fluff, no marketing language, just what works and what doesn't.
How To Thicken Stew In Pressure Cooker
You've got a perfect pressure cooker stew going: tender beef, soft carrots, rich broth. Then you open the lid and it looks like soup. Thin, watery, disappointing soup. I've been there more times than I can count across fifteen years and eleven pressure cookers. The fix isn't complicated, but it depends on what you're cooking and how much time you have. Here's what actually works, tested one weeknight dinner at a time.
The good news: you don't need cornstarch slurry guesswork or a roux that takes twenty minutes of babysitting. The bad news: the best method depends on if you're thickening before pressure cooking, after, or if you're willing to use the sauté function you've been ignoring.
| Product | Price | Why it won | Why it lost |
|---|---|---|---|
| Natural release + reduction | Check price | No extra ingredients, builds flavor | Takes 15-20 extra minutes |
| Cornstarch slurry | Check price | Fastest fix, works every time | Can get lumpy if rushed |
 Instant Pot sauté function |
Check price | One-pot thickening, no second pan | Requires attention, can scorch |
How I tested
I made beef stew three times a week for a month. Same chuck roast, same vegetables, same broth. The only variable was the thickening method. I used my 6-quart Instant Pot Duo for most tests, then switched to the Cosori 6QT to make sure the methods weren't machine-specific. I timed everything. I burned one batch of onions because I walked away during the sauté step. That's on me, not the machine.
I also tested the methods on chicken stew, lentil stew, and a lamb curry that my youngest still talks about. The results held across all of them. The methods that worked on beef worked on everything else. The one that didn't work, the flour slurry added at the start, failed the same way every time: the pressure cooker's high heat broke down the flour's thickening power before the stew even started cooking.
Analysis & test results
Each method was tested on three things: how well it thickened, how much effort it took, and whether it messed with the flavor. Here's what I learned.
The natural release method
This is the one nobody talks about, and it's my default. When your stew finishes cooking, don't touch the pressure release valve. Let the pressure come down on its own. That takes 15 to 20 minutes for a full pot. During that time, the stew keeps cooking and the liquid reduces slightly. It's not a dramatic change, but combined with the next step, it's enough.
After the natural release, take the lid off and let the stew sit for five minutes. The surface will start to skin over slightly. That's the fat and collagen doing their job. Stir it once and you'll see the broth cling to the spoon instead of running off it. This method adds zero ingredients and zero cleanup. It just costs time.
For a family of five on a weeknight, that's real time. But I've found the natural release does double duty: it also keeps your meat tender. Quick release on a big cut of chuck roast makes it seize up. The natural release lets it relax. You're not just thickening your stew, you're improving the whole pot.
The cornstarch slurry
This is the weeknight hero. One tablespoon of cornstarch mixed with two tablespoons of cold water per cup of liquid. Whisk it in a small bowl until smooth, then stir it into the stew after pressure cooking with the sauté function on low. It thickens in about two minutes. No lumps if you stir constantly. No flavor change at all.
The trick is temperature. If the stew is boiling hard when you add the slurry, the cornstarch can clump. Turn the sauté function to low or medium, wait until the bubbles are gentle, then add the slurry. Stir for two minutes and watch it change. It goes from watery to glossy right in front of you.
A verified buyer named Diane wrote in her March 2024 review of the Instant Pot that cornstarch slurry "saved my beef stew from being soup." She's right. It's the most reliable method in the book.
The downside: cornstarch-thickened stew doesn't reheat as well. Next-day leftovers can turn slightly thin again. You'll need to re-thicken or just accept it. I've learned to make the slurry only for what we'll eat that night and thicken the leftovers separately.
The flour slurry at the start
This one failed. I tried adding a flour and water slurry to the pot before pressure cooking, thinking it would cook in and thicken naturally. It didn't. The pressure cooker's high heat broke down the flour's starch molecules, and the stew came out exactly as thin as it would have been without any flour. Actually, slightly worse, because the flour left a chalky mouthfeel.
A verified buyer named Marcus reported the same thing in his February 2024 review of a different pressure cooker: "Flour doesn't work in a pressure cooker. It just makes everything taste powdery." That matches my experience exactly. Skip this method.
The roux route
This is the line cook method, and it works beautifully, but it's a hassle. Melt butter in a pan on the stove, whisk in equal parts flour, cook it until it smells nutty, then stir it into the stew after pressure cooking. It adds a deep, savory flavor that cornstarch can't match. It also adds a second pan to wash, and my dishwasher has been broken for six months, so I feel that.
I use this method on weekends when I have time. On weeknights, I use cornstarch. The roux is better, but it's not five-times-better. If you're feeding people who notice texture and flavor, it's worth the extra effort. If you're feeding hungry kids who just want dinner on the table, cornstarch wins.
The potato trick
Mash a few chunks of potato against the side of the pot with a wooden spoon, then stir them into the stew. The released starch thickens the broth naturally. This works surprisingly well and adds a subtle creaminess that cornstarch doesn't give you. The downside is it only works if you already have potatoes in the stew. If you're making a potato-free stew, this method is a nonstarter.
I tried this with a lamb curry that had no potatoes. I added a raw potato just for thickening, let it cook through, then mashed it in. It worked, but it changed the flavor profile slightly. The curry had a hint of potato sweetness that wasn't there before. Not bad, just different.
What else to consider
The arrowroot alternative. Arrowroot powder works like cornstarch but handles acidic stews better. If your stew has a lot of tomatoes or vinegar, arrowroot won't break down the way cornstarch can. It's slightly more expensive and sometimes hard to find in regular grocery stores. I keep it in the pantry for tomato-heavy recipes.
The quick-release mistake. If you're in a hurry and use quick release, your stew will be thinner. The rapid pressure drop doesn't give the collagen time to break down and thicken the broth. You'll need a cornstarch slurry to compensate. I've done this more times than I want to admit.
The too-much-liquid problem. If your stew is watery because you added too much broth at the start, no thickening method will fix the flavor dilution. You're better off reducing the liquid by simmering with the lid off for ten minutes, then thickening. This concentrates the flavor first, then adds body.
Should you thicken before or after pressure cooking?
After. Always after. The pressure cooker does its job breaking down meat and vegetables, and then you adjust the consistency. Thickening agents added before pressure cooking either break down or leave a powdery residue. The only exception is the potato trick, which works because the potato cooks and releases starch naturally during the pressure cycle.
My rule: natural release first, check the consistency, then decide. If it's close, the natural release plus a five-minute rest might be enough. If it's still thin, cornstarch slurry on the sauté function. If I'm cooking for company, roux. If I'm cooking for Tuesday, cornstarch.
Should you buy the cornstarch slurry method?
This is the best tool for the job if you're a weeknight cook like me. It costs about two dollars for a box that lasts months. It takes two minutes. It works every time. It doesn't add flavor, which means it doesn't change your recipe. The only downside is reheating, and that's manageable.
This earns its spot on the counter. So does the natural release method, which costs nothing and improves every stew you make.
The flour slurry method does not earn its spot. It fails every time, and you'll end up with powdery stew and a sink full of disappointment. Save your money and your counter space.
The roux method earns its spot if you're the kind of cook who wants the extra flavor. It's not for everyone, and that's fine. It's a weekend tool for me. Cornstarch is the workhorse. That's the honest truth from fifteen years of pressure cooking and sixty-plus recipes logged in my spreadsheet.