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Using a slow cooker seems simple, and it is— at least in theory. Simply throw everything you need for your recipe into the appliance, turn on the heat, and wait. A few hours later, you’ll find a fully-cooked dinner waiting for you. That’s damn easy, right?
While one of the most obvious benefits of this cooking method is how low-maintenance it is, it’s important to note that the process isn’t always entirely that straightforward—especially if you’re still getting to know your slow cooker. From learning which food ingredients you can and can’t put in your slow cooker to how much liquid you should add, there’s a lot to keep in mind as you transition from slow-cooker novice to pro.
If you’re someone who has been unhappy in the past with how your slow cooker recipes have turned out, you’ve come to the right place. Of course, this is a no-judgment zone, but if you’ve had some sub-par slow-cooker meals, it might be because you were making one of a few common slow-cooker mistakes. SELF spoke to people who really know their Crock-Pots (and other slow cookers) for their top slow-cooker intel so you’ll get perfect results every time.
Can you overcook something in a slow cooker?
Slow cookers are specially designed to cook food for long periods of time, but yes, you can still overcook in a slow cooker if something is left on the wrong setting for longer than it’s supposed to be.
To keep this from happening to you, heed advice from Sonali Ruder, D.O., an emergency medicine physician, chef, and founder of The Foodie Physician (she also loves slow cookers). “If you’re cooking meat, you’ll know it’s done when it is fork-tender, meaning you can cut into it easily with just a fork,” she says. When meat is overcooked, it will be “tough and dry,” while overcooked vegetables will be mushy. It may take some trial and error to learn the ins and outs of what tips food over to “overdone” on your machine. Being a doc and all, Dr. Ruder also advocates for food safety: Another way to check if your food is done is by using an instant-read food thermometer. “Cook meat to 145-160 degrees Fahrenheit, poultry to 165 degrees Fahrenheit, and soups, stews, and sauces to 165 degrees Fahrenheit.”
Can you stop slow cooking and start again?
It is not recommended to stop slow cooking and start again, otherwise you risk falling into what the USDA calls the “danger zone” for food, which is 40-140 degrees Fahrenheit.
“This is the temperature range at which bacteria (like Salmonella and E. coli) grow the most quickly, so you want to avoid having food sit at this temperature for too long otherwise you run the risk of getting sick,” explains Dr. Ruder. “Technically, you could stop and restart a slow cooker for a short period of time if you don’t let the food get below 140 degrees Fahrenheit, but I wouldn’t risk it.”
What cannot be cooked in a slow cooker?
As convenient as slow cookers are, they don’t work for everything. Here are some things you should proceed with caution with when it comes to tossing them in your slow cooker (especially if you’re considering leaving these ingredients in there for a long stretch of time):
- Dairy products: If you toss in milk, half-and-half, or cream with all your other ingredients right away, it’ll likely end up curdling. If you’re making a creamy stew, Alexis Davidson Kornblum, the recipe developer behind Lexi’s Clean Kitchen, tells SELF she recommends adding the dairy ingredients only in the last 15 minutes of cooking.
- Frozen food: Cooking frozen food of any kind in a slow cooker can be dangerous. Sara Haas, R.D.N., tells SELF that as frozen food thaws out in a slow cooker, it can fall into the aforementioned danger zone. While it may seem more dangerous to add frozen meat than frozen veggies, they’re actually both risky. “Although many people put frozen vegetables into the slow cooker, you technically shouldn’t,” Dr. Ruder says, noting that it puts you at risk for foodborne illness. “The next time you plan to use your slow cooker, try to remember to take your meat and veggies out of the freezer and put them in the fridge to thaw out overnight so that they’re ready to go the next day.”
- Seafood: Fish and shellfish can overcook and fall apart when put in a slow cooker at the very beginning, as Glenna Vance and Tom Lacalamita write in their book Slow Cookers for Dummies. These ingredients, they write, usually turn out best when added in during the last 30 to 60 minutes of cooking.
- Certain vegetables: Delicate herbs and veggies like fresh tomatoes, zucchini, and peas won’t fare well in the slow cooker, as their individual textures may become mushy and flavorless if left for too long. If your recipe calls for these vegetables, try adding them close to the end of cooking time.
- Chicken skin: Most slow-cooker recipes ask you to remove chicken skin before adding it to a slow cooker. If you skip out on this step, be warned that it’s not going to come out with crispy skin like it would if it were roasted—the texture will be more rubbery, which is not exactly appetizing.
- Rice: Quick-cooking rice can infamously turn to mush in your Crock-Pot. In his book Toss & Go!: Featuring Quick & Easy Pressure Cooker & Slow Cooker Recipes, author Eric Theiss writes that you should add it in during the “last 30 minutes or so of cooking time.” (Long-grain rice, though, can withstand several hours of cooking time slightly better.)
- Pasta: Pasta can easily become overcooked and mushy in your slow cooker. Add it in during the last 30 minutes, writes Theiss.
Should food be covered with liquid in a slow cooker?
According to the University of Minnesota, meat and poultry should be covered with liquid in a slow cooker. The University of Minnesota notes that “the water or liquid level should cover the ingredients to ensure effective heat transfer throughout the crock.” With vegetarian recipes, Vance and Lacalamita write in Slow Cookers for Dummies to use about one cup of liquid (unless it’s a soup, which would understandably call for more).
Why is my beef tough when I make it in the slow cooker?
“Beef may be tough in the slow cooker if you haven’t added enough liquid, or haven’t cooked it for long enough,” Kristen Carli, M.S., R.D., owner of Camelback Nutrition & Wellness, tells SELF. “For cuts of meat, the fattier cuts are often the ones that get juicy and tender. If you use cuts of meat that are too lean, you will notice they [are more likely to] dry out.”
If you consistently notice tough beef, Carli says your slow cooker may not be working hard enough. “Try cooking for longer, or at a higher temp,” she advises.
Is it safe to leave a slow cooker on overnight?
The short answer: Yes. slow cookers are made to cook food for extensive periods of time (some can be left up to 24 hours). But, of course, follow safe practices outlined in your instruction manual, and keep the appliance on low or warm, as opposed to high, overnight. “[Low] will keep it at a safe temperature (usually 145-165 degrees Fahrenheit) until you’re ready to eat,” says Dr. Ruder. “Keeping the slow-cooker on the high setting for that long may result in overcooked, dried-out food.”
Now that you’ve gotten the basics of how to use your slow cooker, you’ll want to level up your chef skills and maximize your flavor from each dish.
These are the top mistakes to avoid when you’re slow cooking your meals.
If you’re throwing raw meat straight into your slow cooker, know that there are better ways. Kornblum tells SELF that while, yes, you technically can slow-cook with raw meat, you won’t get your best results this way. You’ll have better luck in the flavor department if you sear it first— browning adds a nice, caramelized depth to the dish.
There are no cuts of meat that are fully off-limits in a slow cooker, but chef Michele Sidorenkov, R.D.N., recommends marbled and fatty pieces, as well as tough cuts of meat because they’re “full of collagen and connective tissue” that break down nicely over a long period of time. “When cooked low and slow in the slow cooker, both will slowly start to dissolve, giving you an incredibly tender bite of meat.”
As mentioned earlier, chicken skin, no matter how long you cook it, will never reach a terribly delicious state if it spends too long in a slow cooker. Even if you do your due diligence and sear skin-on chicken before you put it in your slow cooker, odds are it’s going to end up mushy and rubbery. If you really, really want to cook it with the skin on, what Kornblum recommends doing is broiling it for a few minutes after it’s finished in the slow cooker “to crisp it up.”
If you add a bunch of salt to a dish at the very beginning (you know, when all the ingredients are still raw and you can’t actually taste it yet), Christopher M. Wilmoth, corporate chef at Hong Kong–based food company Lee Kum Kee, tells SELF you’re more likely to end up accidentally over-seasoning. “If too much stock, sauce, or seasonings are added to the slow cooker before or during the cooking process, a dish that seemed properly seasoned may end up tasting too salty,” he explains. Your better bet? Season with a teeny bit of salt at the beginning, and do the heavy-duty salting at the finish.
Fresh herbs taste best, well, fresh. If you add a sprig of thyme or rosemary to your Crock-Pot at the very beginning, it will likely wilt, brown, and become nearly flavorless by the time your meal is ready. A better option? Add dried herbs in the beginning—so the different ingredients in your dish have time to meld—and finish it off with the fresh ones. That way, they’ll add a nice, bright refreshing punch to your dish.
How much liquid goes in your slow cooker? If you’re converting a traditional recipe to your slow cooker, be wary of adding too much—you should cut the amount by about half since the lid traps moisture instead of letting it cook off. Again, make sure meat is fully covered in liquid, but otherwise keep it on the low side.
Slow cookers should be “at least halfway, but no more than two-thirds full,” write Vance and Lacalamita. Anything less may cause your food to overcook, and conversely, if it’s too full, your food may not cook fully.
Keep in mind that since the heat source of slow cookers like the Crock-Pot is at the bottom, you should first throw in the food items that take the longest to cook. The U.S. Food and Drug Administration advises starting with raw vegetables followed by meat or poultry. More delicate items should cook towards the top of the appliance.
Peeking is tempting, but don’t do it. Wilmoth explains that slow cookers work by trapping heat. “Every time you remove the lid, the slow cooker loses heat,” he tells SELF. If you absolutely must remove the lid before it’s done (maybe you have some last-minute ingredients to add), Kornblum says to get in and out as quickly as possible—30 seconds max. So, seriously, forget about it, let your slow cooker do its thing, and be ready to dine in a few hours.
This doesn’t apply if you’re mainly cooking soups or stews, but many sweet slow-cooker recipes call for a non-stick cooking spray to prevent a mess and simplify the cleanup process. You can also use oil or butter. “If you are making some kind of [dessert] slow cooker recipe, like a slow cooker cake or brownie, then I would absolutely grease the slow cooker beforehand,” Sidorenkov tells SELF. “Also, if your slow cooker is more of a multi-cooker with the ability to sear before slow cooking, I would recommend adding some kind of oil to the cooking surface to keep your ingredients from sticking while browning.”
While this is the least likely to cause a bad meal of all of the slow-cooker mistakes, it might just be a game-changer. Another mess-free option? Slow cooker liners ($6, Amazon).
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