American cooks have frequent affairs with spiralizers, dry fryers and other shiny new toys. But they also have a deep, lasting relationship with one of the oldest cooking tools in the kitchen: the cast-iron skillet.

“There aren’t many things in modern life that are passed down through generations and remain both beautiful and useful,” said Ronni Lundy, a historian of the food and agriculture of Appalachia, where cooking in a well-seasoned heirloom skillet is a touchstone of heritage.

It’s true that my grandmother’s china is gathering dust. Your great-grandfather’s gold watch (admit it) lies unused in a drawer. But my parents’ 50-year-old cast-iron pans, with their glassine black cooking surfaces, are the inheritance I crave.

“I have two that are just coming along now,” Lundy said in the nurturing tone usually reserved for children, sourdough starters and rosebushes.

Well-seasoned cast-iron pans are the new broken-in jeans: proof of both good taste and hard use. New companies are promising to make improved cast-iron skillets with a combination of traditional handwork and modern technology.

And cast-iron collecting has taken off. Buyers seek rare skillets like the Erie Spider, the Griswold Slant and the Wapak Chickenfoot; a Sidney No. 8 is listed on eBay for $1,500.

The roots of devotion

With cast iron’s mystique comes mystery. The responsibility of seasoning a pan can be daunting; the idea of a pan that is never washed with soap can be alarming. But it is worth overcoming these obstacles because a well-used, well-seasoned cast-iron skillet is truly an all-purpose pan: nonstick enough to cook eggs, hot enough to sear anything and completely functional for roasting, stewing, simmering and baking.

“You can caramelize a crust in cast iron in a way that would never happen in a sheet pan,” said Charlotte Druckman, who has just written a book on cast-iron baking.

The nonstick surface is achieved with natural ingredients like flaxseed oil, lard and time, not with synthetic coatings like Teflon.

For all these reasons, even cooks without a tradition of cooking in cast iron now want to start one.

The Field Co., run by Chris and Stephen Muscarella, raised more than $1.6 million on Kickstarter; their first pans will ship soon from a foundry they built in the Midwest. The Finex company in Portland, Ore., is making 200 skillets a day and barely keeping up with demand, according to Mike Whitehead, a founder.

The Field skillet sells for about $100. A 10-inch Finex skillet sells for $165; an equivalent from Borough Furnace company is $280.

Why pay nearly $300 for a modern “artisanal” cast-iron skillet when a perfectly functional equivalent from the venerable Lodge company costs $16 at Walmart?

The answer lies in craftsmanship. Cast-iron implements made in the United States from the 18th century through the first half of the 20th were different from today’s: lighter, thinner, smoother.

A labor-intensive process

The Muscarella brothers wondered why their new cast-iron pans were so unwieldy compared with their mother’s old ones.

Those old pans were poured and polished by hand, a process that required hours of human labor but yielded a noticeable difference.

“I fell in love with that smoothness,” said Whitehead. “But now that I make them, I realize why it went away. Labor is just so expensive.”

Nostalgia for old ways of cooking is powerful but also practical.

“Cast iron is not responsive, but it is relentless,” said food scientist Nathan Myhrvold. No common cooking material has such a high “thermal mass,” or ability to absorb heat.

Myhrvold said the common notion that cast iron is a good conductor of heat is a myth; in fact, the opposite is true. Cast iron grabs heat and holds onto it.

“After you put the steak in contact with it, there’s a lot of spare heat left to cook with,” he said. “Cast iron doesn’t drop in temperature as much as thinner pans with better conductivity,” such as aluminum and stainless steel.

In Appalachia, cast iron survived when modern cooks switched to lighter pans, which heat quickly on gas and electric stoves, Lundy said.

“That skillet became part of the imagery of the Appalachian woman,” said Lundy, whose family lived for at least four generations in Corbin, Ky., making everything from pork chops to cornbread, cobblers and even biscuits in cast iron. “The first thing any mountain cook will tell you is the history of her skillets.”

Soon the same might be true of all cooks. Whitehead said a customer recently bought a Finex skillet after his first son was born. “The dad wants to start using it now,” he said, “so it will be ready for the boy when he turns 18.”

Flattened Chicken Thighs With Roasted Lemon Slices

• 9 bone-in, skin-on chicken thighs, rinsed
• 18 sage leaves
• 3 to 4 large cloves garlic, peeled and thinly sliced (to yield 18 slices)
• 4 teaspoons kosher salt
• 2 lemons, rinsed
• Fresh thyme or oregano sprigs, for garnish

>> Marinade:

• 9 large strips lemon peel (from 2 lemons)
• 1/4 cup fresh thyme or oregano leaves
• 1-1/2 tablespoons chopped sage leaves
• 1-1/2 tablespoons chopped Italian parsley
• 10 to 12 medium or large cloves garlic, peeled and smashed
• 1 teaspoon red chili flakes
• 3 tablespoons extra-virgin olive oil

Pat chicken pieces dry with paper towels. Using your fingers, gently separate the skin of each piece from the flesh, leaving the skin attached at one end, to create a deep pocket between skin and flesh. Tuck 2 sage leaves and 2 garlic slices under skin of each piece.

Combine marinade ingredients in bowl. Put thighs in bowl, turning gently to coat. Cover bowl and refrigerate at least 2 hours or overnight.

When ready to cook, remove thighs from marinade and place them skin side up on a baking sheet. (Reserve garlic cloves and lemon peel from marinade; discard liquid.) Sprinkle 2 teaspoons salt over chicken, then turn and sprinkle with remaining 2 teaspoons salt.

Transfer 5 thighs, skin side down, to a 10- or 12-inch cast-iron skillet. Put it over high heat and weigh down the chicken with the bottom of another cast-iron skillet. (Or, use a lighter skillet weighed down with a large full can, a brick or another heavy object. Make sure the bottom of the skillet is clean, or place a sheet of parchment paper between chicken and top skillet.)

Once chicken is sizzling loudly, reduce heat to medium and cook without moving for 10 to 12 minutes, until skin is brown and crisp. To check for doneness, gently lift corner of a thigh with a spatula. The skin will come away cleanly from the pan when it is done. If it is still stuck, do not pull, but let it cook a little longer.

When thighs are done, remove weight and lift chicken out of the pan, taking care to keep the skin attached. Transfer, skin side up, to a clean baking sheet or plate. Cook remaining 4 chicken thighs in the same way. Pour off most of the fat from the skillet.

Meanwhile, heat oven to 450 degrees. Halve lemons and squeeze gently to remove some of the juice. Cut crosswise into 1/8-inch slices and lay on paper towels to absorb more juice.

Place a layer of lemon slices in skillet. Lay chicken pieces on top of lemons, skin side up. Tuck reserved lemon peel and garlic cloves between the pieces.

Transfer skillet to oven for 20 to 30 minutes, until juices run clear and there is no redness near the bone. Remove pan from oven and let thighs rest in the pan 5 to 10 minutes.

Tuck thyme or oregano sprigs around thighs and serve from the pan, with roasted lemon slices and garlic cloves. Serves 6 to 9.

Nutritional information unavailable.