ONCE YOU SINK YOUR TEETH into duck confit, you’ll know why chefs go to the trouble of making it. “I love to eat duck confit wherever I go, so that’s why we serve it,” says Daniel Crocco, of Brasserie 292 in Poughkeepsie. Brasserie 292 opened only at the beginning of summer, but already the crispy duck confit on frisée salad is so popular Crocco can hardly keep up. In August, his team was making it three times a week and he’s determined to have it on the menu year ‘round.

Confit might sound like fancy French food but, in fact, its origins are strictly peasant class, born out of the need to preserve food in the ages before refrigeration. Broadly speaking, the technique has come to mean the slow cooking of fruit, vegetables or meat in an immersion, usually of fat— the method might be one of the oldest forms of preservation known, alongside salting, smoking and pickling. The French root word is confire, a verb meaning to produce or prepare—it was first applied to the processing of fruits in sugar or honey. (Thus derives our English word confection, still used today to designate exquisite sweets.)

In On Food and Cooking: The Science and Lore of the Kitchen (Scribner, rev. ed., 2004; $40 hardcover), Harold McGee says that from ancient times it was known that meat could be preserved for long periods if salted well, cooked in fat (usually rendered from the meat), then stored in that fat, which congeals as it cools and seals the meat away from invading oxygen, the enemy of preservation. But under that seal, magical tastes developed in the meat as it aged and underwent chemical changes. Confit can be used on almost any food—you may spot tomato confit on menus, or onion confit—though duck, sometimes goose, are more common.

A key to confit, says Jonathan Pratt, of Peter Pratt’s Inn in Yorktown, is that it drives out the water present in meats or vegetables but leaves behind rich, concentrated flavor.

“You can confit the toughest, gnarliest piece of an animal and get the most wonderful flavor,” Pratt says. Lamb and beef shoulder are perfect candidates, but even fish can be done confit. What’s important, he says, is a temperature high enough to drive off water but low enough to prevent frying.

At the Brasserie, Crocco applies a 60/40 mix of sugar and salt, allspice, clove, garlic and thyme for the curing phase. The legs go into the fat overnight in 180 ̊F oven. For the dish, the confit is crisped in a frying pan and served with sautéed shiitake, oyster, and brown and white beach mushrooms served with frisée dressed in a mustard vinaigrette.

Donna Hammond, chef and owner of Hudson Street Cafe in Cornwall-on-Hudson, salts her duck legs judiciously with coarse Kosher salt in the curing stage so they won’t need rinsing before the fat immersion. “You salt them as you would salt a steak to grill it,” she says.

After two days of curing in the refrigerator, she arranges the legs skin-side down in a pot, each on a bay leaf, a clove of garlic and a sprig of thyme. She covers the legs completely in melted duck fat and simmers them over low heat for three or four hours. Hammond prefers the cook top over the oven so she can adjust the heat as necessary. “I like to watch it,” she says, “and make sure it’s not overcooking,.”

After cooking, she strains the duck fat and reuses it in the next batch. Chef Crocco does, too, noting the oil eventually acquires a rich, dark gold hue. “It just keeps getting better and better,” he says.