From cooking stones and stone boiling, to curanto, pachamanca, and sangak, stones can throw some culinary weight around, with history as rich as its recipes.
Pot Boilers
No, we don’t mean takeout dumplings. Pot boilers or cooking stones, were fist-sized stones used to heat water, originally by cultures without access to metal vessels or pottery capable of withstanding direct heat. What makes such stones of interest to archaeologists and anthropologists is the thermal stress story relayed in their repeated exposure to fire, followed by rapid cooling in water. Expansion and contraction of a
cooking stone over time can lead to a partial glazing and telltale network of cracks on its surface called crazing.
“The pot boiler was a roughly rounded stone, usually flint, made red hot and flung into water contained in a primitive cauldron or in puddled hollow in the soil. By this means flesh was boiled, however inefficiently, or the meat was grilled or baked over the heated stones. The use of the pot boiler for heating water was continued until late in the historic period,” cited Walter Johnson in his 1908 ‘Folk-memory: or, The continuity of British archaeology.’
According to curators with the Royal Alberta Museum, plains people used cooking stones in boiling pits constructed underground, because the prairie winds were so strong they would cool above-ground containers faster than the stones could heat
the water inside.
Photo Se.Xauxa, Spanish Wikipedia GNU Free
Documentation
Cooking Stones: Curanto
Curanto, from Mapudugun, kurantu, for ‘stony ground,’ is a Chilean one-pot method of cooking food using heated rocks buried three feet deep in an earth oven and covered
with turf and wild rhubarb leaves. Gastro Obscura suggests this ancient equivalent of the New England Clambake is the world’s oldest recipe. Since the 1970s, archaeologists at Monte Verde have found some of the earliest evidence of humans in South America, including clay-lined burn areas where radiocarbon analysis dates 14,500 to 19,000 years ago.
Curanto is about preparation more than the recipe and ingredients can vary from pit
to pit, and century to century. After lining a hole with rocks, a wood fire is set to heat
the stones. When the fire burns down, the ingredients (shellfish, smoked meat, chicken, sausage and potatoes) are loaded into the hole before covering it with wild rhubarb
leaves, damp sacks and packed dirt. As the shellfish cooks, its shells pop open, releasing
more flavored juices to sizzle on the rocks and steam the feast.
“Everything emerges slicked in juices and oils, and since the large pits lend themselves
to feeding crowds, curanto tends to enliven family gatherings and special occasions,” concludes the food adventurer’s guide.
rocks are shoveled inside. Wiki/GNU Free Documentation.
Cooking Stones: Pachamanca
Pachamanca is from Peruvian Quecha, pacha, for “earth” and manka for “oven” or “pot.” Andean families have used hot stones to bake in a huatia, or earth oven, since the
Incan Empire. Cooking food underground pays homage to Pachamama, the goddess of earthquakes and it is still an efficient option for making a lot of food for a lot of people, as large or whole pieces of meat can be roasted with side dishes like habas (lima beans), chuño (potatoes), and edible tubers like mashua and oca.
“In the U.S., a big celebration usually means cake. In Peru, it’s all about the pachamanca, which translates to a big hole dug in the ground that cooks up an entire meal,” says Serious Eats blogger Katie Quinn. “It’s ancestral comfort food.”
Once the earth oven has been dug, the hole is lined with bricks. Rocks heated over fire become the heat source, Quinn says, and once shoveled in, the oven is ready. “But not any rock will do. Only volcanic rocks can withstand such intense heat without cracking
or popping.”
Bushcrafters attest that lava rocks can “retain serious heat” and make a good choice for underground and pit cooking. The downside is porousness, where sauces or juices can seep in, making them less hygienic in the long term.
Cooking Stones: Sangak
“As the story goes, every soldier would carry two or three stones in his pocket and when the army camped for the night, each would take their stones and put them in a big pile in a pit. They would build a fire on top of the stones and let it heat for a couple of hours, then brush off the embers. Then the baker would throw flatbread onto the hot stones. They were able to cook for three or four hours on hot stones,” shared Master Baker, Michael Hanson, in a ‘Breads from the Hearth’ workshop, during a virtual Kneading Conference sponsored by the Maine Grain Alliance.
Sangak, also known as Pebble Bread or Persian Army Bread, is a flatbread baked on
hot stones. What kind of stones? Interestingly, recipes from skilled bakers go into great detail about leaveners, proofing, and cold ferments but as to the type of roughly three
pounds of stones to bake with, the most common requisite is… clean. Preparing stones for baking begins with several rounds of washing and rinsing to remove oils or dirt. “Just to be sure,” adds BreadExperience.com, “boil the stones for 10 minutes in a pot of clean water.” After draining, dump them onto a rimmed cookie sheet to dry and once dry, they are ready to use.
“Sometimes after baking there are bits of bread stuck to one or two stones,” an Our Kitchen blogger, Elizabeth, told Bread Baking Babes when featuring Wild Naan
Sangak as its bread of the month. “To remove the bread, soak stones in clean water and the bread will come right off. When not using them for baking, let them cool, make sure they’re dry, and keep them in a jar or container.”
cooking, with meat placed on stones and covered with moss or leaves. Image Future Museum South West Scotland collection
Stone Soup
Which stones make good cooking stones? Meaning, can they prove their durability, ability to retain heat and – most importantly – resistance to thermal shock (cracking)? Stones to be avoided include the obviously fragile, like quartz, shale, slate or “glassy-looking” rocks. Slate may be metamorphic and formed under pressure, but its thickness and how quickly it is heated can compromise its durability.
Better cooking stones choices include granite or volcanic rocks like peridotite. Stones that have already formed naturally under extreme geologic pressure and heat (like granite) aren’t going to melt over a little old clambake.
“Granite can withstand higher temperatures and heat transfers well, making it good
for cooking different kinds of food. Granite can also withstand low heat, meaning it can
cope with being stored outside,” reviewed WildwayBushcraft.co.uk for ‘Cooking On A Rock – What we’ve learnt so far.’
“Not all rocks are equal,” these outdoor cooking experts said. “Rocks form in different ways and this will impact how they respond to heat. Some work well, some are rubbish, some are dangerous. Be sure the rock you’re going to use doesn’t contain toxic minerals. If there is anything questionable inside it is likely to leach into food when under a stressor like heat. Be sure of your rock identification and formation.” The ideal cooking rock is hard, non-porous, even in density with no internal flaws and strong [sedimentary] bedding planes that occurred in the formation process.
Not sure you’re ready to rock cooking stones yet? You can always rely on your
rock-collecting family for support. Let the fable of Stone Soup lead the way: More can be accomplished when people work together because every little bit that someone has to give matters.
Happy cooking!
This story about cooking stones previously appeared in Rock & Gem magazine. Click here to subscribe. Story by L.A Berry.
