Besides being designed to reach "optimal" cooking temperatures upward of 425 to 540 C (800 to 1,000 F), demand has grown "exponentially" since Allan Ham started selling the ovens five years ago.
Propane and gas-fuelled variations on traditional ovens are being carried by major retailers.
Some homebuilders are including this old-fashioned, wood-fired "technology" in high-end, indoor kitchens, says Ham, owner of Outdoor Pizza Ovens in Shanty Bay, Ont., near Barrie.
Although the construction materials are better today, the classic ovens have changed little in centuries — a stone hearth covered by a stone-lined dome with a chimney. There is insulation behind the stone and the outside can be stucco, brick or mosaic tile.
But the traditional wood-fired ovens, with cooking surfaces from 30 to 112 centimetres (12 to 44 inches) or larger, don't come cheap. Even medium-sized ready-made units start at more than $2,000 and the largest, most elaborate ones can be closer to $9,000 (shipping and stands not necessarily included).
Ham sees potential in a Finnish-inspired product that's not much bigger than a suitcase, sits on a picnic table, uses wood pellets as fuel and heats to more than 425 C (800 F) in 10 minutes. It costs $400.
"But here's the thing. If you buy a little one, you're going to wish you had a bigger one," says Ham, who says the most popular size cooking surface with his customers is 91 centimetres (36 inches).
About half his buyers buy kits to build their own, but even those run from about $1,200 to $5,000.
So why invest thousands of dollars to return to a form of cooking that's been around for millennia?
"I think we're all drawn to fire," Ham says. "It's in our DNA. The oven door's open all the time and you see the fire and you see your food cooking right before your eyes."
It's very social, with guests able to create and bake their own pizzas.
"And ultimately it's the taste of the food" and the wood smoke that gives even familiar dishes a new flavour.
There are two basic kinds of wood-fired outdoor ovens.
In a "black oven," the wood burns on the stone floor. Depending on the oven's size and quality of the wood, it takes 45 to 90 minutes to heat the oven to optimal temperature, Ham says.
Although often called "pizza ovens," black ovens can be used as smokers and to bake, roast and grill. You can set a grate inside and cook over the coals as you would on a barbecue or brush the wood and ash aside and cook directly on the hearth.
Either way, the extreme temperatures radiating from all sides of the dome make cooking very fast — about 90 seconds for a pizza, for example.
It retains the heat so well that an oven heated to optimal temperature in the evening will still have an internal temperature of 180 or 200 C (350 to 400 F) the next morning — enough to bake bread.
In "white ovens," the fire chamber is below the oven. You don't have to clean up wood or ash, but "they don't hold their heat into the next day or you can't grill in that oven. It's just basically an oven or a smoker."
While propane or natural gas ovens are more economical at a few hundred dollars, heat up in about 10 minutes and cook a pizza in about five minutes, they aren't much different than indoor ovens and don't offer the experience of a wood-fired oven.
Learning to use the ovens takes practice; food can burn quickly.
"People don't realize how quickly food cooks at such high temperatures," Ham says.
"But once you cook a few dishes, you start to understand how these things cook. And because it cooks on all sides, it's amazing."
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