The Wonderbag Slow Cooker Bag: Should I Buy One?

What is a Wonderbag slow cooker? This insulated bag keeps pans of food warm for up to 8 hours. Once your pot of food has simmered for 15 minutes, take it off the heat source and use the Wonderbag to continue the cooking process. It lets you slow cook without using electricity. Can it be as good as it sounds?

Our product-tester Kate puts the Wonderbag through its paces to find out...

"With energy prices on the rise, we’re all looking for ways to reduce our bills. With a Wonderbag, you can cook food for up to eight hours - no energy required. It’s portable, eco-friendly and can be left unattended until you’re ready to eat.

I took one home for a week and tried out a few of my favourite slow-cooked recipes. Here are the recipes I tried, some top tips I picked up along the way, and my overall review.

Wonderbag slow cooker in action

What is the Wonderbag?

The Wonderbag was created by Sarah Collins as a solution to the South African energy shortage, which forces blackouts across the country. The aim was to help families to continue cooking daily meals even with the absence of power. Time spent collecting firewood, cooking and tending a fire can now be spent in education or employment.

In countries where cooking over fire is the norm, Wonderbags can reduce carbon emissions and indoor air pollution. Less firewood is required, saving trees from deforestation.

Wonderbag Non-Electric Slow Cooker, Green

The green Wonderbag comes in two sizes. The medium bag will hold a pot that is 6 litres in capacity. The "in-use" dimensions of medium are: 38cm x38cm x20cm.

The large Wonderbag will hold a 10-litre cooking pot. And when fully expanded measures 47cm x47cm x22cm.

How does the Wonderbag work?

The colourful drawstring bag uses heat-retention technology to continue cooking food once your pan has been removed from the heat source. It’s filled with chipped recycled foam which acts as insulation. With no additional gas or electricity being used, you can lower your energy bills and reduce household emissions from cooking by up to 70%.

Once your food is brought to the boil, place it in the bag and it will continue cooking for up to eight hours.

    I spent a week with the Wonderbag, here's what I learnt

    After spending some time doing my research, I put the Wonderbag through a week of rigorous testing. Where better to start than with a much-loved French classic - boeuf bourguignon

    I used medium sized pieces of beef shin and a heavy cast iron pan. Once the meat was browned and the wine and stock had come to the boil, I placed it in the Wonderbag and pulled the drawstring tight.

    After four hours, the beef was perfectly tender and the sauce had transformed into a rich, glossy gravy. It was hot enough to serve straight away and had the same deep, savoury flavour you would expect from long, slow cooking.

    I had similar success with a simple bolognese sauce, leaving it in the Wonderbag for five hours while we shopped for fresh pasta and parmesan. Much like a conventional slow-cooker, you can leave the Wonderbag unattended - ideal for busy work days.

    How to get the best from your Wonderbag:

    1. Use a pot or pan with short handles and a tight fitting lid. Long pan handles will stick out of the bag.
    2. For best results, choose a pot that will be almost full with your recipe. This will help maintain the ideal cooking temperature.
    3. Put a tea towel or wooden chopping board inside the bag to prevent the material from discolouring in any way.
    4. Place the Wonderbag on a heat-proof mat or trivet while it’s in use, to be extra sure the heat won't mark your surface.
    5. Make sure you leave your hot Wonderbag out of reach of children or pets while it is slow cooking.

    Wonderbag Non-Electric Slow Cooker, Red

    Wonderbag puts social impact at the heart of its business. Here's how they describe their impact: "When a Wonderbag is used by women in developing countries, it transforms lives. Time that was previously spent collecting firewood and tending the fire, can now be spent in education, employment, or setting up their own business. Wonderbag therefore acts as a catalyst for female empowerment and resilient communities, helping to support all 17 Sustainable Development Goals along the way."

    Other ways to use the Wonderbag

    The Wonderbag also comes in handy for keeping dishes warm while you’re travelling. A pan of tarka dal, fragrant with garlic and curry leaves, was still hot after a three hour car journey.

    It’s also ideal for meal prep days when your oven or hob is full - the Wonderbag will sit happily on a heat-proof mat on the dinner table. I used it to finish cooking a pot of braised Puy lentils while I fried onions and Toulouse sausages. The lentils emerged piping hot and full of flavour, with no extra energy required.

    I was impressed with the Wonderbag’s versatility and the rich, slow-cooked flavour it gave our dishes. If you’re cooking larger or tougher cuts of meat, you might not get the same fall-apart result that a traditional slow-cooker would offer but trial and error is the key. We found that chicken thighs, minced beef and vegetarian dishes turned out perfectly.

    Wonderbag Non-Electric Slow Cooker, Turquoise

    Why do fans of Wonderbag love it so much?

    ⭐⭐⭐⭐⭐ "I made a Mexican inspired Chilli - browned the meat and brought up to temperature on the hob for 10min, then into the Wonderbag for 6 hours. Very much a set and forget situation as you don't have to worry about anything burning, any heat being too high, or forgetting to turn it off. After the 6hours were up it was still steaming hot, and absolutely delicious. Super handy with handles as well, as you can get it going in the morning if you're going somewhere, and still bring homecooked fresh food to a friends place, without needing to guard it and wait for it to be done. It's cooking for you on the go!" - Kristin, Cookware Buyer

    ⭐⭐⭐⭐⭐ "I was really surprised how well the bag retained the heat. Will be using it a lot for stews"

    ⭐⭐⭐⭐⭐ "I cooked the food then put it into the bag and 2.hrs 30 minutes it was still pipping hot. Very happy, will try and leave it for longer tomorrow."

    ⭐⭐⭐⭐⭐ "Amazing product, saves on electricity and the food is amazing."

    What to cook in the Wonderbag slow cooker?

    Try this slow-cooked pork pibil which is absolutely delicious. If you’re looking for something plant-based, Eleanor Ford's Sri Lankan pumpkin curry always hits the spot.

    You can also use your Wonderbag for keeping sweet dishes such as rice pudding warm or Mexican arroz con leche.

    Final thoughts: Should I buy a Wonderbag?

    If you’re looking for ways to reduce your energy consumption, the Wonderbag is a great addition to your kitchen.

    After a bit of trial and error, you’ll be surprised at how many dishes you can cook in it. I've read reviews from people using Wonderbags to slow cook safely on boats, caravans and camping trips. It will also keep food and drinks cold, so you could fill it with snacks for your next picnic or trip to the beach.

    The Wonderbag is ideal for small kitchens as it can be squashed flat and stored in a cupboard. You can spot clean it or wash it on a cold, gentle washing machine cycle.

    For dishes with heaps of slow-cooked flavour, this eco-friendly bag is hard to fault. Plus, when you buy one, you’re investing in the environment and supporting the Wonderbag manufacturing community in South Africa.

    Browse our full collection of wonderbags or find more articles on our bureau of taste.


    • Can a Wonderbag be used simply to keep food warm rather than cook it?

      Cherry on

    • That’s a great question. What size casserole do you usually cook in?

      Nicola - Sous Chef Team on

    • Wonnderbag certainly beats the non transportable hay bale wrapped in a duvet method of yesteryear lol

      Steph Mc on

    • A wonderful idea and I would love to buy one, but perhaps someone can give me a bit more info. I live alone and would do not be cooking family-sized meals. Would even the medium be a bit big for me?

      Jane on

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