Onsen tamago (Japanese 温泉卵 or 温泉玉子) or onsen eggs are eggs cooked in Japan’s hot springs, called onsen. Unlike conventional boiled eggs, they are usually cooked for around one hour at temperatures between 60 and 70°C, whereby both egg white and yolk only coagulate slightly and obtain a uniformly waxy consistency, comparable to lost eggs. (..)
With the spread of the low-temperature method in Western gourmet cuisine, the method of preparing onsen ice cream was also adopted and refined. Christian Lohse, for example, serves peeled onsen eggs breaded in panko and briefly deep-fried, giving the very soft eggs a thin, crispy coating.
So what you want to achieve is a firm-creamy, almost waxy texture to the yolk. Before serving, it is separated from the egg white, because both components of the ice cream behave completely differently. In the protein, ovotransferrin first begins to set at about 60°C, but this protein makes up only about 12% of the protein. Ovalbumin, on the other hand, which accounts for around 54% of protein, requires at least 80°C and therefore initially remains liquid. In between, somewhere around 62 or 64°C is the temperature at which lipovitellin and phosvitin, the two main proteins in egg yolks, become solid. This temperature must therefore be achieved with relative precision.Our recommendations for cheap and good sous vide equipment
In my setup, I use the Fusionchef Diamond, which was kindly provided to me by Julabo for testing purposes.
So, since the temperature to be selected is fixed, the variable component consists of the time you want to allow the egg to reach the desired cooking point. Of course, the size as well as personal preference plays a decisive role. For medium sized eggs, you would probably choose 45 minutes for a still slightly runny yellow, and expect around 60 minutes for a more waxy-firm yolk.
The question remains, of course, what to do with the onsen egg after its preparation. After several attempts and repeated tastings I can credibly assure: Pure it is not a pure pleasure. Due to the waxy texture and the strong intensity of the flavor, a very complex, very strongly lining mouthfeel is created. But, it is a fantastic companion that can carry many dishes to whole new impressions thanks to this very complexity.
Playing with texture is another approach to variation, for example in bringing the yolk into a crispy shell. To do this, you can bread it á la Christian Lohse in panko and deep-fry it very briefly. In my test run, I served it with chili strands and red-green chili salt with vanilla (that’s right, Schuhbeck). Theoretically, the egg white can also be included here, because the 54% ovalbumin, which had previously remained liquid, should also set in the hot fat. But for this, it would have to succeed in completely breading the entire egg, despite its different, partly liquid consistency…
A much more pragmatic variant, is the combination with fresh, light and seasonal products, whether vegetables or mushrooms, which ideally combine harmoniously with the soft egg. Mushrooms and chanterelles have worked well in my trials, if you like you can shave some truffle over the egg to make the combination even denser.
Dishes with eggs have recently become more established in the menus of upscale restaurants, as they offer a wide range of culinary possibilities with extremely low product input. The onsen egg certainly stands out in particular. But with the right equipment and a little practice, it’s easy to do at home. The demand is, as with many things in life, rather in the coherent accompaniment…
Steaming and sous-vide
- Herbicht, Markus (Author)
