Help needed on “natural sous vide”

Eggs boiled in onsen (japanese: hotspring), Nagano, Japan (Photo: Miya.m. Permission: GFDL, cc-by-sa-2.1-jp).

In Japan eggs cooked in hot springs (onsen) are known as onsen tamago. I’ve also read that Māori women used boiling pools at Whakarewarewa to cook. In fact I wouldn’t be surprised if many people with access to hot springs would have considered using them for cooking. But finding examples isn’t so easy, so now I need your help: Are you aware of other examples of “natural sous vide”? By this I mean cooking of food at temperature below 100 °C/212 °F without the use of a temperature controlled water bath. It could be in a hot spring, near volcanoes, in steam baths or even in saunas (in a previous post on eggs I mentioned Finnish sauna eggs and Korean Maekbanseok gyeran). Any help finding other examples would be greatly appreciated! I’m interested in modern-day examples as well as traditional practices.


  1. I was recently in Pantelleria south of Italy, and one of the harbours (Gadir) had hot springs in it. The hottest one was painful to put your hand in, but not instantly scalding, so I’d guess it must have been around 60C. One of the locals told me that it was used for cooking, but he didn’t tell me what was cooked in it. As it was a bit pongy and had a fair few dead crabs/fish that had wandered too close to the heat, and loads of seaweed (both dead and lightly poached, and living and clearly heat-resistant), I guess eggs would be a good choice – you might not want to eat something where the bit you eat had been poached in that primordial soup!

  2. I know you specified “sous vide”, but it sounds like what you’re really after is “water-based food handling with nature-assisted temperature control”. After all, the photo you used doesn’t look like anything has been done “under vacuum”.

    I live in a part of the Rocky Mountains not known for hot springs. However, cold streams aren’t uncommon, and I have seen many a camper store cold foods and drinks in shallow streams to keep them cold, rather than using a cooler full of ice.

    In terms of actual cooking, I have heard of people in Hawaii sneaking into protected land with specialized equipment to do some cooking with lava overflow (this is apparently not uncommon). In one such story, people wrapped a cornish game hen in several layers of banana leaves and shoveled hot lava (!) over it. With the moisture from the banana leaves, this is essentially a steaming method.

  3. Thomas: Interesting example!

    Joseph: You’re absolutely right. This has nothing to do with the literary meaning of “sous vide”, but I couldn’t think of a better short description. And you’re right by stating that what I’m really after is nature-assisted temperature control (but I would also like to expand that to include other “uncommon” examples of temperature control).

    Brandon: you say “cooked” – was the earth/ground hot?

  4. Martin: what Brandon is talking about sounds like a good old-fashioned clam bake (among other things). There are variations, and similar techniques are common in Tropical islands such as Hawaii. The basic idea is, dig a hole, add hot coals (often by building a fire in the hole, to create the hot coals), add leaves or seaweed, add the food to be cooked, cover with leaves or seaweed, and optionally bury the hole for several hours or days. Anything from seafood to whole pigs can be cooked this way.

  5. Dishwasher salmon was always a go to dinner party dish at my house. A 2-3kilo side of salmon with butter, lemon, white wine and fennel top wrapped in foil and put through a wash. I guess about 70-80 degrees for maybe 45 minutes. Detergent is best omitted.

  6. Martin, when my wife and I were on our honeymoon in Ireland 5 years ago, we visited the Irish National Heritage Park near Wexford. While there, we saw a demonstration of Fulacht Fiadh: the educator dug a hole in the earth, lined it with stones, and filled it with water. He then heated several large rocks over a fire and dropped them in to the water until it was steaming hot. Finally, he had a haunch of venison, seasoned and wrapped in leaves, that he lowered into the water and was going to cook that way for several hours, periodically adding more hot stones from the fire.

    It’s not really nature-assisted, but certainly a similar technique.

  7. This was a common method used by Maori in New Zealand. Here’s an image from 1910. You can see this today in touristy places in Rotorua. Some more images: 1, 2, 3 (modern).

    You also might find the ‘hangi’ (in wider Polynesia, the ‘umu’) of interest, where heated rocks are buried along with the food. Depending on the method and the amount of greenery used to wrap the food, this can be anywhere along the scale from steaming to grilling.

  8. The Cypriot\Greek dish Kleftiko (or Klephtiko) is of meat cooked in the ground, and has a nice story, as mentioned here:
    “Kleftiko orignated in the 1800’s and the word kleftiko means stolen meat in Greek. Kleftiko got its name as it was made with either lamb or goat that would have been stolen from flocks grazing on the hillside. The stolen meat would then be cooked in a hole in the ground filled with hot stones and embers and then sealed by packing soil over the top so that no smoke or steam would escape. This method meant that the thief would not be drawing attention to their ‘ill-gotten’ gains. The dish would sometimes cook for up to twenty four hours like this”.
    These days it is prepared in the oven, and is nonetheless delicious.

  9. there is of course cooking in compost heaps and straw piles which can be used for making yogurt, cheese etc as well as cooking eggs, and slow cooking meat. Make sure you wait after piling everything up for the heat to really get going. I have always wondered about the possibility of building a little oven of some description within the compost heap which could be accessed easily from outside…

  10. and thankyou martin for your compliment in the twitter feed on the right, which I didnt see on twitter becasue you wrote to beanreade. only my mum calls me bean – ben is better for being in contact! al the best and thanks for feeding my brain with ideas! – will you be coming to MAD?

    • Wow – never heard about cooking in a compost heap before, but yeah – it makes sense since the temperature stays below 70 C. And I apologize for getting your twitter name wrong! In fact I may be able to participate a little as I’ll be in Copenhagen August 26-27.

  11. Hi Martin

    There are some examples in Portugal, particularly in the Azores island of S. Miguel. In Furnas the traditional meal – cooked daily by many restaurantes for local and tourists, but also by families – is the a meal of meat and vegetables cooked in the ground by the geo-thermal heat.
    You can see some photos, and a description of the process, here:

    There they also cook bags of corn cobs in hot springs.

    I have been there last summer and I have some photos that I can send to you.

  12. Hi Martin,
    When I visited the volcanic island of Tana, Vanuatu, I saw the Ni Vanuatu (natives) cooking eggs and plantain in the volcanic hot springs. The temp was controlled by selecting different parts of the hot spring stream that mixed with cold water.

  13. My first venture with natural sous vide was the summer I was five. It was accidental and revolutionary: I sat my dish of freshly picked peas on our deck in the afternoon sun while I played with my dolls. Ten to fifteen minutes later, I noticed their colour had turned astoundingly vibrant. Drawn by their allure, I tasted them and a powerful vision immediately opened that this is what food was for – to give us exhilaration and joy as it nourishes us! I intuitively knew it was the wealthy way to go: noster pater parochus; effortless, pure and, unlike the examples given thus far, with zero risk of contaminating precious water.

  14. Icelanders have been using hot springs and other sorts of geothermal energy for everything from bathing to heating to cooking.

    It is a typical tourist trick to boil an egg in a hot spring, but I don’t think that is really an old traditional thing.

    Bread has often been baked by burying it in the warm ground in hot spring or geothermal areas. “Hverabrauð” or “hot spring bread” is a typical Icelandic rye bread which has been cooked in the ground.

    There’s a description of hot spring cooking in Iceland as well as a picture of egg boiling here:

    I’ve often seen the sheep in the steamy Reykjadalur valley enjoying the heat from the hot springs. It would be interesting to see if the long term steam exposure affects the meat. The ultimate steam cooking.

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