KEY TAKEAWAYS
- Prep: 5 min | Cook: 8 min | Total: 13 min | Serves: 1
- Ratio: 200ml dashi per 100g cooked rice — soupy, not porridge
- Rinse leftover rice 10 sec under cold water to remove surface starch
- Add egg last, off heat, lid on 30–60 sec — slightly wobbly is correct
- Zosui does not keep — eat immediately, rice absorbs broth within minutes
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Zosui Ingredients
For 1 serving. Scale linearly: 2 people = double everything.
- 150g cooked Japanese rice (any variety — leftover from the day is perfect, fridge-cold is fine — see how to store cooked rice so the leftover is safe to use)
- 250ml dashi (or leftover nabe broth — this is the ideal case)
- 1 tbsp soy sauce
- 1 tsp mirin
- 1 egg
- 1 spring onion, thinly sliced (garnish)
- Yuzu zest if available (garnish — see what is yuzu)
- Mitsuba (optional garnish)
How to Make Zosui
- Rinse the rice. Run the cooked rice under cold water for about 10 seconds, gently separating the grains. This removes excess surface starch and prevents the zosui from becoming gluey. Drain well.
- Heat the broth. Bring 250ml dashi to a simmer in a small pot over medium heat. Add soy sauce and mirin. If using leftover nabe broth, taste first — it may already be fully seasoned.
- Add the rice. Add the rinsed rice to the simmering broth. Cook 4–5 minutes, stirring occasionally, until the rice softens and absorbs dashi flavor. The consistency should be soup-like, not porridge-like.
- Add the egg. Beat 1 egg lightly. Pour in a thin stream around the edge of the pot (not the center — pouring into the center creates a single clump). Cover immediately, turn off heat, wait 30–60 seconds. The egg sets from residual heat — slightly wobbly is correct.
- Serve immediately. Transfer to a bowl. Add spring onion and yuzu zest. Do not let it sit — the rice continues to absorb broth and the texture changes within minutes.
What makes this work
The classic use case: after nabe (hot pot), the remaining broth has concentrated dashi flavor plus everything that leached from the meat and vegetables during cooking. Adding cold cooked rice to this broth, simmering 5 minutes, and cracking an egg in is the traditional way to close a nabe meal. This is why zosui and nabe are culturally linked — the rice course uses the broth that the main course built.
The standard ratio: 200ml dashi per 100g cooked rice per person. This produces a soup-like consistency — the rice is suspended in broth, not sitting in a small amount of liquid. If you want it thicker, reduce to 150ml per 100g. If you want it more like broth with some rice floating in it, increase to 300ml.
Why rinse the rice: pre-cooked rice has a coating of gelatinized surface starch. In a fried rice recipe, this starch is useful (it helps grains separate in the wok). In zosui, it turns the broth cloudy and heavy. A 10-second rinse under cold water removes enough starch to keep the broth clear and the soup texture light.
Zosui Variations
- After nabe: use the leftover nabe broth directly as your liquid. Add rice, simmer, add egg. No extra seasoning is typically needed — the broth already has layers of flavor from the nabe ingredients.
- Oyster zosui (kaki zosui): add 6 fresh oysters to the broth in the last 2 minutes of cooking. Season with soy sauce only (skip the mirin — you want the brininess to come through). A winter specialty in Japanese coastal regions.
- Egg-drop style: instead of covering the pot after adding the egg, pour the beaten egg in a thin stream while stirring the soup continuously. This creates ribbons of egg throughout the broth rather than a soft-set layer on top.
Frequently Asked Questions About Zosui
What is the difference between zosui and okayu?
Okayu starts with raw rice and a lot of water (5:1 ratio), cooked from scratch for 40–50 minutes until the grains break down into a smooth porridge. Zosui starts with pre-cooked rice and dashi, cooked briefly (5–8 minutes) — the grains soften but retain some texture, and the result is more like a soup with rice in it than a porridge. Okayu is plain and mild; zosui is savory, flavored by dashi and soy. Zosui is what you make after nabe; okayu is what you make when someone is sick or when you want the simplest possible bowl.
Can I use any type of rice for zosui?
Yes. Japanese short-grain rice is ideal because the starch structure holds up well during simmering without dissolving completely. But zosui is fundamentally a leftover-rice dish — it works with medium-grain, long-grain, and even brown rice. The texture will differ: long-grain stays more separate and less creamy; brown rice stays firm longer and may need an extra 2–3 minutes of simmering. Mochi rice (glutinous rice) is not recommended — it becomes too sticky and gluey.
Can I use instant dashi for zosui?
Yes. Instant dashi (dashi no moto / hondashi) works well for zosui. Dissolve according to package directions — typically 1 tsp granules per 250ml hot water. The flavor is simpler than fresh dashi but for a quick weeknight zosui it is perfectly practical. If you have leftover nabe broth, use that instead — it already has layered flavor from the meat and vegetables.
Why rinse the cooked rice before adding it to the soup?
Pre-cooked rice has a layer of surface starch that makes zosui thick and gluey rather than brothy. A 10-second rinse under cold water removes enough of this starch to keep the broth relatively clear and the soup texture light. If you skip the rinse, the result is closer to okayu in consistency — not wrong, but heavier than zosui is meant to be.
Is zosui good for sick days?
Yes. Zosui is one of the standard Japanese comfort foods for illness and recovery, alongside okayu and umeboshi. The warm dashi broth is hydrating and easy to digest, and the egg adds gentle protein. The key advantage over okayu for sick days is speed: zosui takes 8 minutes from fridge to bowl, while okayu takes 40–50 minutes. If the sick person can handle some flavor (dashi, soy), zosui is more satisfying. If they need the blandest possible option, plain okayu is better.
How long does zosui keep?
Zosui does not store well. The rice continues to absorb broth as it sits, turning what was soup into thick porridge within 30 minutes. Make it fresh and eat it immediately. If you have leftover dashi and leftover rice, store them separately and combine just before serving. The whole cooking process takes 8 minutes, so there is no real advantage to making it ahead.
Where to go next
- Recipes — the full practical cooking section
- What Is Dashi — the broth that makes zosui work
- How to Make Dashi — fresh dashi from kombu and katsuobushi
- Okayu — the from-scratch rice porridge (raw rice + water, 40–50 min — different technique, different result)
- Miso Soup — another simple Japanese soup built on dashi
- What Is Yuzu — the citrus garnish that lifts zosui from good to excellent
- The Japan Times — Food & Drink — further reading on Japanese home cooking culture
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