Some high-end restaurants are starting to look more like laboratories than kitchens. On the counters where raging-hot broilers once sat, immersion circulators (water-calibrating equipment originally used in medical laboratories) now quietly churn. Cooks who used to wear neckerchiefs to catch the drips from the blasting ovens now favor crisp white aprons. They drop vacuum-sealed plastic packs of lamb into swirling 140.5-degree water -- not a degree more or less.

This is not to say that good restaurants have forsaken high heat. Nothing blisters the skin of a roasted pepper, chars a burger or crisps the base of hash browns quite like a good blast of fire.

But sous vide (soo VEED), which cradles the food in plastic before cooking it gently in a warm-water bath, has sunk its hooks into the cooking world, probably for the long run. The use of vacuum-packing and low-temperature poaching originated in France in the 1970s, and has steadily crept its way across the ocean and into top kitchens in the United States.

The effect is high-tech, oddly void of cooking aroma. But the food that emerges from those pouches silences all doubters: The meats are succulent, flavorful and juicy. Vegetables cook to the point of firm-but-tender perfection and taste like model specimens of themselves, frontrunners for natural selection. After two hours of slow poaching, cherries look the same as they did going in, but their flavor has been intensified.

Though it inspires visions of boil-in-a-bag peas in butter sauce, this isn't your grandmother's sous vide. This hyper-attention to temperature is teaching professional cooks radical new things about ordinary foods. Inevitably, what they learn will trickle down to change the way we all cook at home -- for the better.

A new cookbook just came out to help guide us into the (literally) tremulous waters of sous vide. Thomas Keller, chef of the famed French Laundry restaurant in California's Napa Valley, has written "Under Pressure: Cooking Sous Vide," which tells of his use of sous vide in fastidious detail. The glossy photos of jewel-colored cubes of compressed melon and graceful stacks of translucent white asparagus logs are stunning, pure eye-candy for any foodie. This book was intended for restaurant chefs to consult and home cooks to drool over, but nonetheless, some of the recipes will work in the home kitchen.

Although it may look like culinary shenanigans, sous vide isn't really about the gear, bags and circulators. It's about heat. For the first time in history, cooks can precisely control the heat source and cook proteins and vegetables at temperatures well below the point of boiling (212 degrees F).

Harold McGee, author of "On Food and Cooking" and the well-regarded king of kitchen chemistry, breaks it down like this: When the temperature of meat reaches 140 degrees, the cell walls begin to contract and squeeze out moisture. Subjected to high heat, the temperature quickly accelerates to 160 degrees and the fibers contract further, breaking some of the cell walls and pushing moisture outward. The meat swells and begins to toughen. Some of the lost juices (which contain the bulk of the flavor) will be reabsorbed by the damaged cell walls if the meat is allowed to rest, but most of them will end up pooling in the bottom of the pan. (Hence, the reason for gravy.)

With sous vide, the protein cell-walls expand, but the heat is slow and low enough that they don't break. Chicken breast cooks to a dreamy tenderness; the well-done slices are floppy enough to curl around a spear of asparagus and brim with juice.

In many ways sous vide is easier than roasting. Much of the timing and guesswork needed to roast at high temperatures isn't required with sous vide. For a steak cooked to medium, you can poach it in 140-degree water until it reaches an internal temperature of 140 degrees. Depending on size, it should take about 30 minutes. Then if you want caramelized edges, you can sear it quickly on all sides in a hot oiled pan. When sliced, an even pinkness will stretch from edge to edge. Overcooking is impossible and you'll never see another rare bull's-eye at the center of your steak.

Sous vide also transforms sturdy vegetables, such as carrots, potatoes, fennel bulbs and artichokes. Cooked at 185 degrees (about 10 degrees below a simmer), artichokes cook to a perfect doneness -- tender but not mushy. And because the vacuum packing prevents oxidation, the artichokes keep their pale, lime-green color. Slicing through them reveals a delicate network of violet veins that I've never noticed in braised artichokes.

In the early days of sous vide in New York (back in the '90s), cooks at the four-star Bouley poached chicken breasts in buttermilk and quail with foie gras, each in a low-tech way: with cryovac bags, a big, wide pot full of hot water, a good-quality probe thermometer and a watchful eye.

That's the best home set-up. In my experience, the larger the pot, the better. A greater volume of water will maintain a more consistent temperature. It also helps to have a probe thermometer to gauge the water, preferably a programmable one that alerts you when the temperature dips either below or above the mark.

One caveat (a very important one): You must be as vigilant about the temperature of the food before and after cooking as you are during cooking. Foods that go into the bag must be cold. Hot foods coming out must be either consumed right away or thoroughly chilled in an ice bath and stored in the refrigerator. Because the vacuum creates an airless (anaerobic) environment, botulism is of particular risk if you allow your cryovacked food to laze around at room temperature. But following the cook's maxim -- keep hot food hot and cold food cold -- will prevent problems.

That said, cooking sous vide at home should be fun, playful and experimental. Mix freshly dug potatoes with bacon fat or toss salmon with your best extra-virgin olive oil before cooking. For the most tender shrimp you've ever had, cryovac raw shrimp with orange zest and olive oil, throw the package in the water and watch the doneness slowly creep into the shrimp as its pearly white flesh deepens to coral pink.

Once bitten by the sous vide bug, you may start seeing possibilities for it everywhere. For example, after a messy, failed attempt at sealing pears in a simple toffee poaching liquid with my FoodSaver -- it doesn't handle overly juicy marinades -- I turned to a very old-fashioned solution: a wide-mouth pint jar.

The pear fit snugly inside and the poaching liquid reached halfway up its sides. Tightly sealed and poached at 180 degrees in a water bath, the pears absorbed the toffee flavors and cooked to a velvety softness. (This isn't technically sous vide because the fruit isn't under vacuum. But it uses the same principles -- very slow cooking and close marination of sous vide.)

Amy Thielen is a chef and writer who splits her time between Two Inlets, Minn., and New York City.