Onsen Tamago: Hot Spring Eggs

If you’ve ever wandered into a trendy hipster brunch spot, chances are you’ve seen slow poached eggs. Slow cooking has come back into fashion in a big way, and even eggs haven’t escaped unscathed. But as much as Australia’s new wave of café owners and breakfast aficionados may try to pass these eggs off as a new trend, the truth is they’ve been around for generations.

Onsen Tamago—literally ‘hot spring eggs’—have been gracing Japanese plates for hundreds of years. The traditional method uses rope nets to lower eggs into the onsen (about 70°C), where they are left to poach in their shells for 30–40 minutes. The result is a silky, translucent white and a custard-like yolk, all golden and viscous and delicious. It’s usually served in bonito dashi (a delicious broth) and is more of a snack or side dish than a breakfast food. But then again, so are hash browns.

One of the fantastic elements of this dish is the texture contrast between the whites and the yolk. This is down to simple chemistry: egg yolks solidify at 70°C while the whites solidify at around 80°C. As the cooking temperature hovers around 70°C, the whites and yolk stay a little bit fluid, resulting in the most delightful mouth-feel.

This recipe will get you perfect Onsen Tamago every time.