Cooking sous vide is easier than its fancy name might suggest. You simply seal the ingredients in a plastic bag (you can also use a canning jar) and place them in a water bath, a combi oven, or any other cooker that can set and hold a target temperature to within a degree or two. When the food reaches your target temperature or time, you take it out, give it a quick sear or other finish, and serve it. That’s it.

The sous vide method yields results that are nearly impossible to achieve by traditional means. In the photo above, both of the tenderloins started at the same weight. The steak on the left was cooked in a pan to a core temperature of 52 °C / 126 °F, but more than 40% of the meat was overcooked. The other steak was cooked sous vide to the same temperature and then seared with a blowtorch to yield a juicier steak that is done to perfection from edge to edge.

Similarly, beef short ribs braised at 58 °C / 136 °F for 72 hours are melt-in-your-mouth tender, yet pink and juicy. And the delicate, custard-like texture of an egg poached at precisely 65 °C / 149 °F is amazing.

Sous vide is especially useful for cooking meats and seafood, for which the window of proper doneness is often vanishingly small when traditional methods are used. When you fry a piece of fish, the flesh is most succulent and tender within a very narrow temperature range. Because the cooking temperature of the pan is at least 200 °C / 392 °F hotter than the ideal core temperature of the fish, the edges will inevitably be far more cooked than the center when pan-fried.

Chicken breasts and other poultry cuts and poultry products are often held at a target temperature for a different reason: to kill potential pathogens and improve the safety of the food.

The idea of preserving and cooking food in sealed packages is ancient. Throughout culinary history, food has been wrapped in leaves, potted in fat, packed in salt, or sealed inside animal bladders before being cooked. People have long known that isolating food from air—accomplished more completely by vacuum sealing—can arrest the decay of food. Packaging food also prevents it from drying out.

Although sous vide literally means “under vacuum” in French, the defining feature of the sous vide method is not packaging or vacuum sealing; it is accurate temperature control. A computer-controlled heater can warm a water bath to any low temperature you set, and it can keep it there for hours—or even days, if needed.

Such mastery over heat pays off in several important ways, most notably, freeing the cook from the tyranny of the clock. Traditional cooking with a range, oven, or grill uses high and fluctuating temperatures, so you must time the cooking exactly; there is little margin for error. With just a moment’s inattention, conventional cooking can quickly overshoot perfection.

When cooking sous vide, in contrast, most foods will taste just as good even if they spend a few extra minutes at a target temperature, so you can relax and devote your attention to the more interesting and creative aspects of cooking.

Precise temperature control and uniformity of temperature has two other big advantages. First, it allows you to cook food to an even doneness all the way through—no more dry edges and rare centers. Second, you get highly repeatable results. The steak emerges from the bag juicy and pink every time.

A final important benefit is that the closed bag creates a fully humid environment that effectively braises the food, so ingredients cooked this way are often noticeably juicier and more tender. Food cooked sous vide doesn’t brown, but a simple sear adds that traditional flavor where needed so that you can have the best of both worlds.

We’ve been asked many times about the safety of cooking plastic bags. The bottom line is that bags made expressly for cooking sous vide are perfectly safe—as are oven bags, popular brands of zip-top bags, and stretchy plastic wrap such as Saran Wrap.

The plastic that these products are made of is called polyethylene. It is widely used in containers for biology and chemistry labs, and it has been studied extensively. It is safe. But, do avoid very cheap plastic wraps when cooking. These are made of polyvinyl chloride (PVC), and heating them presents a risk of chemicals leaching into the food.

Cooking sous vide isn’t complicated or expensive. In Modernist Cuisine at Home, we guide you through the various kinds of sous vide equipment and supplies available for home cooks, including how to improvise your own setup. Check back later in the week when we share such methods using equipment you probably already own.