Onsen Tamago (hot spring egg)

Onsen Tamago (hot spring egg) in dashi

This is probably my favourite dish of all time. It’s not even so much a dish as much as a preparation. “Onsen” means “hot spring” in Japanese and “tamago” means “egg.

Since Japan sits on top of a giant volcano, there are hot springs all over the place. Some of these hot springs happen to be be exactly 160 degrees F which is the perfect temperature to slow cook eggs. For those that have never had one, it’s one of those experiences where you take a bite and exclaim “I had no idea eggs could taste like this!”.

The white has the texture of a really delicate custard while the yolk comes out firm, but retains the color and creamy texture of an uncooked yolk. The traditional way to eat them is for breakfast covered in seasoned bonito dashi, but I love these so much I put them in just about anything. In noodle soups, donburi’s, butternut squash soup, or on fried rice. I’ve even contemplated turning it into a dessert with a sweet caramel syrup (a deconstructed creme caramel).

I won’t lie to you, they are tricky to get right, but with the right equipment and a couple of try’s you should be able to get it just right. The difficult part is in keeping the temperature just right. All you need is an instant read thermometer, a heavy pot with a lid (like a Le Crueset), and a timer. If you’re lucky enough to have an oven that can accurately maintain a temp of 170 degrees it’s even easier.

One last note, the FDA recommends you cook poultry products to 165 degrees F. Since we’re not quite hitting that, the FDA would consider it “unsafe”, but I’ve never gotten sick eating these and I’ve been told that prolonged temperatures above 140 degrees F kills salmonella. Still if you’re nervous about this kind of stuff this might not be for you.

6 free range eggs at room temperature (you may want to make less the first time)
small enameled cast iron pot with lid (like a Le Creuset)

Take the eggs out of the fridge about an hour before you make this so they have a chance to come to room temperature (this is important). Preheat your oven to 170 degrees F (or as low as it will go).

Fill the pot with water and heat over the stove until your thermometer reads 155 degrees F. Gently lower the whole eggs into the water, cover with the lid and place the whole thing in the oven.

This is where it gets a little tricky. You want to slowly raise the temperature of the water from 155 degrees F to 160 degrees. Any cooler and the egg won’t cook, any hotter and you’ll have a soft boiled egg (not the same as a slow cooked egg). For my oven, this means setting it to 170, and putting the pot in for 45 minutes. If your oven doesn’t go down to 170, you’ll need to check the temperature of the water periodically and turn off the oven, then turn it back on to try to keep the temperature under 160.

It may sound like a ton of work, but it’s worth it, and once you make a batch you can keep them in the fridge for up to a week and use them as you need them.

Unfortunately there’s no way to tell if they are done without cracking them open, so you’ll need to rely on your thermometer and timer. To serve, just crack it open into a small bowl and cover with a splash of salted dashi. Good luck!

  • http://www.chocolateshavings.ca/ Chocolate Shavings

    I’m intrigued – this sounds delicious, and safe enough for me!

  • http://www.chocolateshavings.ca Chocolate Shavings

    I’m intrigued – this sounds delicious, and safe enough for me!

  • http://omnomicon.blogspot.com/ aleta meadowlark

    Oooo! I love poached eggs, I bet I’d like this too!

  • http://omnomicon.blogspot.com aleta meadowlark

    Oooo! I love poached eggs, I bet I’d like this too!

  • http://manggy.blogspot.com/ Manggy

    I would love to try this, though I don’t know if my oven handles temps all that well- I’ll need a thermometer :) Maybe this will be a great application for an induction cooker?

  • http://manggy.blogspot.com Manggy

    I would love to try this, though I don’t know if my oven handles temps all that well- I’ll need a thermometer :) Maybe this will be a great application for an induction cooker?

  • http://www.hungryandfrozen.blogspot.com/ Laura @ Hungry and Frozen

    I’m not going to lie, this does sound really fiddly. But you’re a good salesman – it also sounds delicious :)

  • http://www.hungryandfrozen.blogspot.com Laura @ Hungry and Frozen

    I’m not going to lie, this does sound really fiddly. But you’re a good salesman – it also sounds delicious :)

  • http://newlywedcooking.blogspot.com/ sharon

    Sounds like a very precise operation. Perhaps, I’ll just ask you to make me one :)

  • http://newlywedcooking.blogspot.com sharon

    Sounds like a very precise operation. Perhaps, I’ll just ask you to make me one :)

  • http://polycultural.blogspot.com/ Melissa

    Haha, I play a video game called Harvest Moon where you can make eggs in a spring. I didn’t know it was a real thing! Sounds delicious!

    • http://www.facebook.com/profile.php?id=1206443120 Viet Do

      Pretty much everything in Harvest moon is real :D minus the golden milk and the spirits and magical creatures in each game….and the 12 year olds getting married…well then again they ARE very rural

  • http://polycultural.blogspot.com Melissa

    Haha, I play a video game called Harvest Moon where you can make eggs in a spring. I didn’t know it was a real thing! Sounds delicious!

  • http://feedingmaybelle.blogspot.com/ maybelles mom

    When I was in Japan, a friend used to do this. But, when I tried it, my success rate was 50/50. More magic than anything else.

  • http://feedingmaybelle.blogspot.com maybelles mom

    When I was in Japan, a friend used to do this. But, when I tried it, my success rate was 50/50. More magic than anything else.

  • http://hadleyholistics.wordpress.com/ Hadley

    The yolk on your egg is lovely–what brand it is? That was one happy and well-fed chicken!

  • http://hadleyholistics.wordpress.com Hadley

    The yolk on your egg is lovely–what brand it is? That was one happy and well-fed chicken!

  • Marc

    Chocolate Shavings, give it a go it’s a different experience.

    Aleta, if you like poached eggs, you’ll probably like this. It’s not really anything like a poached egg as the whites are much softer, and the yolk isn’t runny, but it has all the best qualities of a poached egg.

    Manggy, I’m not really sure what an induction cooker is, but I’ve heard you can make these in rice cookers using the “keep warm” function, not sure how I’d feel about sticking whole eggs in my rice though….

    Laura, it is a bit fiddly, but once you have it down, you can impress your friends;-) Don’t be discouraged if it doesn’t work out the first time. If they’re under cooked you could always boil the rest and have soft boiled eggs, and if they are over cooked, you’ll just have a softboiled egg that took forever to make.

    Sharon, it takes a bit of practice, but it’s worth the effort:-)

    Melisa, that’s funny, I wonder if there are other things in the game that are real?

    Maybelles Mom, when were you in Japan? Yea, I had a lot of hits and misses, so you really need to document the process you use with your equipment so you can reproduce it every time:-)

    Thanks Hadley, I get them at the Japanese grocery store here in NYC, they’re from Jirdori chickens and are fed a vegetarian diet… whatever that means. I’ve always wondered why our eggs here in the US are so pale and yellow looking, so I was happy to find these ones:-)

  • Marc

    Chocolate Shavings, give it a go it’s a different experience.

    Aleta, if you like poached eggs, you’ll probably like this. It’s not really anything like a poached egg as the whites are much softer, and the yolk isn’t runny, but it has all the best qualities of a poached egg.

    Manggy, I’m not really sure what an induction cooker is, but I’ve heard you can make these in rice cookers using the “keep warm” function, not sure how I’d feel about sticking whole eggs in my rice though….

    Laura, it is a bit fiddly, but once you have it down, you can impress your friends;-) Don’t be discouraged if it doesn’t work out the first time. If they’re under cooked you could always boil the rest and have soft boiled eggs, and if they are over cooked, you’ll just have a softboiled egg that took forever to make.

    Sharon, it takes a bit of practice, but it’s worth the effort:-)

    Melisa, that’s funny, I wonder if there are other things in the game that are real?

    Maybelles Mom, when were you in Japan? Yea, I had a lot of hits and misses, so you really need to document the process you use with your equipment so you can reproduce it every time:-)

    Thanks Hadley, I get them at the Japanese grocery store here in NYC, they’re from Jirdori chickens and are fed a vegetarian diet… whatever that means. I’ve always wondered why our eggs here in the US are so pale and yellow looking, so I was happy to find these ones:-)

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  • http://manggy.blogspot.com/ Manggy

    Marc, it should be no problem to just pour in water into the rice cooker and set it to Keep Warm– freshly cooked rice would likely be too hot anyway. I’d have to check exactly what temperature “Keep Warm”, er, keeps it warm in our model, though.
    http://en.wikipedia.org/wiki/Induction_cooker

  • http://manggy.blogspot.com Manggy

    Marc, it should be no problem to just pour in water into the rice cooker and set it to Keep Warm– freshly cooked rice would likely be too hot anyway. I’d have to check exactly what temperature “Keep Warm”, er, keeps it warm in our model, though.
    http://en.wikipedia.org/wiki/Induction_cooker

  • http://www.eatingclubvancouver.com/ [eatingclub] vancouver || js

    This sounds like brain surgery almost (I had to read it twice) — hence, not my forte. ;) I am however very curious about what slow-cooked eggs taste like, so I might just go against my nature and brave it. Onsen onward then.

  • http://www.eatingclubvancouver.com [eatingclub] vancouver || js

    This sounds like brain surgery almost (I had to read it twice) — hence, not my forte. ;) I am however very curious about what slow-cooked eggs taste like, so I might just go against my nature and brave it. Onsen onward then.

  • http://tastewiththeeyes.blogspot.com/ Lori Lynn

    Fascinating. I have to try this. Love eggs.

  • http://tastewiththeeyes.blogspot.com/ Lori Lynn

    Fascinating. I have to try this. Love eggs.

  • http://www.figandcherry.com/recipes/its-good-to-relax-sometimes/ Christie@fig&cherry

    I am totally intrigued by this Marc – will definitely be giving this a go… by the way, you’ve been eating a lot of eggs lately! ;)

  • http://www.figandcherry.com/recipes/its-good-to-relax-sometimes/ Christie@fig&cherry

    I am totally intrigued by this Marc – will definitely be giving this a go… by the way, you’ve been eating a lot of eggs lately! ;)

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  • http://www.openkyoto.com/ Peko

    Onsen tamago rules! With a bit of dashi, it really will amaze you how wonderful an egg can taste. It is really sad that fresh and clean eggs cannot be obtained in the US. In Japan, it is not just safe to eat underdone eggs, it is safe to eat raw eggs!

    P

  • http://www.openkyoto.com Peko

    Onsen tamago rules! With a bit of dashi, it really will amaze you how wonderful an egg can taste. It is really sad that fresh and clean eggs cannot be obtained in the US. In Japan, it is not just safe to eat underdone eggs, it is safe to eat raw eggs!

    P

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  • http://www.caseyphai.com/ Casey

    I wanted to try this forever after reading it here. Finally bought a thermometer the other day and…I’m ADDICTED…
    The custard-y texture is so goooood.

  • http://www.caseyphai.com Casey

    I wanted to try this forever after reading it here. Finally bought a thermometer the other day and…I’m ADDICTED…
    The custard-y texture is so goooood.

  • Diana

    I’ve had these at the onsen I visited. But I didn’t know it takes that much work to make one. WOW!

  • Diana

    I’ve had these at the onsen I visited. But I didn’t know it takes that much work to make one. WOW!

  • http://www.allpartspoolandspa.com/ spa parts

    That's my favorite breakfast, very informative.

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  • Craig Jenkins

    FWIW I’ve had good success with the warm setting on the rice cooker … but it takes 2 hours! :)

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  • Lum

    I’m from an Asian country, this is a lil Asian innovation, eggs will be easy with this pot/jug/cooker/whatever it ishttp://www.suanie.net/2010/12/09/the-amazing-half-boiled-eggs-cooker/
    just for an example, try to get the yellow thingy for easy egg

  • Natecrawford92

    For anyone thinking about trying this, use a clean cooler!!! They are great insulators, whether it’s hot or cold. I was able to do 20 eggs comfortably in a larger cooler, and just running hot tap water into the cooler occasionally (my tap water turns out to be exactly 155 degrees. I was able to get mine cooked with a very soft custard-like yolk and softer whites, much like what is pictured after about 50-55 minutes in the cooler, very low maintenance, and just maintained water temp every 10 minutes with no need for a thermometer, though I used one the first time but have not used one since.

  • Fancyalyss

    Excuse me, I can see how submerging them in the water and earthy oven, but is there really a difference in taste and composition when using a rice cooker?  It’s just sooooo complicating your version. Wrapping an egg in paper towel, placing them on a bed of cooked rice in the rice cooker and slow cooking is so much easier.  I’m not known for taking the easier way out in ancient food preparations but please advise.  This process seems so painful.

    • http://norecipes.com Marc Matsumoto

      I’ve heard that it works in a rice cooker, so if it works for you then I say go for it. The reason why I posted this technique is because most people don’t have a rice cooker.

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  • Lindafell

    Just made them in my rice cooker in water on the keep warm setting. Got the water to 160 and then put the eggs in for 45 minutes and they came out perfectly.

  • Ari

    I just made these in my rice cooker for the first time. I’m quite sure I will be making these again, and again, and again. XD Thanks for the info! I can’t wait to put this over a steaming bowl of rice.

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I'm Marc, and I want to teach you some basic techniques and give you the confidence and inspiration so that you can cook without recipes too!

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