What is Sous Vide Cooking and How is it Done?

Why should I cook sous vide?

If you’re wondering whether it’s worth investing in yet another kitchen appliance, there are several ways in which a sous vide unit earns its place on your countertop.

The most obvious benefit of cooking sous vide is consistency. With a sous vide unit you have complete control over every aspect of the cooking process. If you’re cooking something expensive, like steak, it's good to have the confidence that nothing unexpected can go wrong.

Cooking sous vide also ensures that none of the flavours of your food are lost. Because cooking takes place inside an airtight bag, all the flavours are sealed inside. Meat cooks in its own juices, and you can seal seasonings inside as well. The sealed bags also mean there’s no cross-contamination. If you’re cooking for several people who all have different preferences when it comes to spicing, you can season each bag accordingly and everyone’s food will be cooked just as they like it.

Convenience is another key factor. Because sous vide is a controlled process, you don’t need to constantly watch over your cooking to make sure nothing burns or boils over. You can set the timer in the morning, go to work, and dinner will be ready when you get home. Or if you’re cooking for friends, you can relax and spend time with your guests while the sous vide cooker does its thing in the kitchen. Even better, there are no pots and pans to wash up afterward.

Misconceptions about sous vide cooking

Most people are still pretty unfamiliar with sous vide cooking, and as with anything relatively new, there are a few common misconceptions. We’re going to take a look at ten of the most frequent.

1. ‘Sous vide is just boil-in-the-bag’. With boil-in-the-bag, the focus is on easy-cook food that can be ready in minutes, which usually involves boiling the food for a couple of minutes until it’s heated through. With sous vide cooking, the aim is to heat food slowly at low temperatures to make it tender without falling apart.
2. ‘Cooking in plastic bags isn’t safe’. Certain plastics can indeed transfer chemicals to food at high temperatures, but the bags used in sous vide cooking are made from food-grade plastics selected specifically for cooking. Plus, the point of sous vide is to cook the food gently, so the plastics are not subjected to high temperatures. Certain cheap plastic wraps may contain harmful chemicals, so if you’re making your own sous vide kit, avoid anything with plasticisers like BPA or phthalates. And if you’re still not sure about plastics, some companies now sell reusable silicone sous vide bags, which are also better for the environment.
3. ‘Cooking at low temperatures won’t kill bacteria.’ We all know that cooking your food at high temperatures helps kill any harmful bacteria that may be living in the food, but in fact cooking at a low and constant temperature inside a vacuum-sealed bag will also effectively sterilise the food. And once the food is sealed inside the bag, there’s no risk of contamination from outside, either.
4. ‘Sous vide is too expensive for home chefs.’ In the past, sous vide units were prohibitively expensive for anyone apart from restaurateurs, but these days there are plenty of affordable home kits on the market. At anywhere between $200-$400, these units are still an investment, but they’re no longer out of reach to most people. And if you want to try cooking sous vide without paying out for a machine, you can make your own using equipment you already have in your kitchen - more of which later!
5. ‘Won’t I need a chamber vacuum sealer?’ A chamber vacuum is a large box, used by restaurants to seal sous vide bags. Bags are placed inside the chamber, which is then closed, and the air sucked out. They’re great for sealing, but they do take up a lot of space, and can be pretty expensive, especially if you’ve just paid for a sous vide cooker.

The good news is that chamber vacuums are not the only way to seal your food. You can get cheaper, countertop vacuums, or even create a vacuum yourself, for free. Simply place the bag in the water bath with the open end above the water and the water pressure will push the air out through the opening.

6. ‘Isn’t sous vide just for meat?’ With so much focus on how cooking sous vide creates the perfect steak, you could be forgiven for thinking this is a method that only works for meat. Maybe you don’t eat much meat, and you’re wondering if it’s worth the hassle for one ingredient. But a sous vide cooker can be used for so much more than just meat. It cooks perfectly tender vegetables without making them soggy, and you can use it to time that perfect, just-runny boiled egg to the second. You can even use sous vide to make french fries or mashed potatoes.
7. ‘I don’t have enough time to wait for sous vide cooking’. There are plenty of recipes that actually take very little time at all. And because you can leave the machine you can do something else while your meal is cooking.
8. ‘Sous vide doesn’t make enough liquid for sauces’. Because sous vide cooks a piece of meat gently, most of the natural juices stay within the meat itself, meaning there is less need for a sauce in the first place.
9. ‘Sous vide takes the creativity out of cooking’. All sous vide does is take the guesswork out of the basics of cooking, leaving you free to experiment with new flavours and ingredients without worrying about whether the food is cooked through, or if your pot is boiling over.

10. ‘You can never overcook food with sous vide’. While it is true you can never burn food using a sous vide unit, if you cook something for too long its internal structure will begin to break down, leaving you with a mushy mess.

What is a sous vide cooker?

A sous vide cooker needs to include some method of heating the water in a cooking pot, either using an induction burner placed below or an induction loop for submerging in the water and pulling it through a heated coil in a circular motion. The heater must then be programmed to maintain a constant temperature and stay active for an exact length of time.

Home sous vide units vary in price between $200 - $400, and some will include a cooking pot already rigged up to the heater, while others are a small heating device that can be attached to one of your own pots. Expensive models may even include their own vacuum sealing devices.

If all of this sounds a little pricey, there are ways you can create your own sous vide rig at home. If you were wondering how McGyver might go about it, check out this super technical hack for turning your slow cooker into a sous vide machine. A word of warning though - playing with exposed wires and water is not for the uninitiated, so maybe leave this one to the mad scientists!

For something a little less challenging, try these simple homemade sous vide kits that can be made using just a thermometer, some ziplock bags and either a cooking pot or a cooler. You will need to check the temperature more often using these methods, but you can still get some great results at a fraction of the price.

Sous vide recipes

If you’re excited to try sous vide cooking yourself, we have some simple, delicious recipes that can be prepared using a shop bought sous vide kit, or your own makeshift rig.

Use your sous vide machine to cook the perfect juicy steak. Seasoned to perfection with salt, pepper and a bay leaf and pan-seared after cooking for extra flavour.

The sous vide machine is great for food with tricky timings, like this flaky salmon fillet, served with a quick cauliflower purée and red bean salad.

You can even use a sous vide machine to cook the perfect poached egg, with a delicious runny yolk.

For these recipes and more check out our collection of 11 sous vide recipes: from steak to egg.

Once you’ve mastered the basics, why not try one of our chef-created fine-dining recipes?

Italian chef Giancarlo Morelli presents a melt-in-the-mouth dish of medium-rare duck breast and thigh, served with beets, potatoes and a sweet and sour sauce, and dressed with sakura sprouts and edible flowers.

Andrea Aprea, chef at the Vun /Park Hyatt restaurant in Milan has created a dish of sous vide lamb loin served with eggplant and plums.

For these recipes and more, take a look at our easy guide to mastering molecular cuisine.