Onsen Tamago

If you’ve ever looked into visiting Japan, you know that onsen (hot springs) are a huge part of Japanese culture – after all, the whole country is part of the Pacific “Ring of Fire,” with plenty of active volcanoes (and earthquakes!). Each onsen has different mineral properties, and many Japanese tourists will pick which onsen to visit based on what ailment they’re trying to heal. That’s where onsen tamago, or hot spring eggs, come in.

One of the popular vendor foods at onsen is “onsen tamago,” which literally translates to, “hot spring eggs.” To a non-Japanese tourist, it may just seem like they’re selling soft-boiled eggs, but it’s more than that. The yolk ends up being custard-y and jammy – it actually holds its shape when you bite into it and doesn’t spill everywhere. The whites are softer than what you’d see in a soft-boiled egg as well; it’s almost liquid-y. The closest way I can describe onsen tamago in terms of preparation, it would probably be sous vide. 

Since every onsen in Japan has different mineral properties, vendors will use that in their marketing as well for onsen tamago. “Don’t just soak in the hot spring; take in the minerals from the inside,” as you will. I’m no scientist, so I can’t say if this is just a folk tale or if it actually has some truth to it, but either way, it’s hugely popular and utterly delicious!

So, if you’re nowhere near an onsen but still want an onsen tamago? You can totally make this at home without using a sous vide machine or any other fancy tools. All you need is a pot, some water, ice, and eggs! The tsuyu sauce is particularly delicious too – if you love the sauce that accompanies soba noodles or tempura in Japanese restaurants, you’ll absolutely love this.

You can enjoy onsen tamago as is (which is the most common method), but this is delicious over rice, or even as a replacement for poached eggs in dishes ranging from eggs benedict to salad, without the hassle that usually comes with making poached eggs. 

Personally, though, I love onsen tamago just by itself, and it’s a fantastic keto or low carb option when you’re tired of Western egg-only recipes. Tsuyu doesn’t have a whole lot of sugar, but if you’re eliminating sugar completely, you can definitely enjoy this with just soy sauce or tamari (if you’re gluten-free).

For other delicious savory Japanese snacks, check out my Okonomiyaki and Agedashi Tofu recipes!

Ingredients

• Eggs
• Hontsuyu
• Water
• Ice

Directions

In a saucepan or stockpot, add enough water so the egg is submerged. You’re just using the egg as a measuring device. All pots are different; remove once you know how much water you need. Bring water to a rolling boil (not a simmer, a full boil).

Remove pot from stove and place on trivet (very important!); add 1 cup room temperature water.

Carefully add 2 – 4 eggs to pot.

Place lid on pot and let sit undisturbed for 15 minutes.

Remove eggs and place into a bowl of ice water to stop cooking.

While eggs are cooling, mix 1 cup cold water to 1/4 cup hontsuyu / mentsuyu concentrate. Usually tsuyu has its own lacquered serving dispenser, but a standard Japanese teapot works for a super cute presentation.

Remove eggs from ice water bath and crack into serving bowl.

Serve with tsuyu (sauce) and enjoy!