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Crystal clear broth, made easy

When we started learning how to cook the various Vietnamese noodle soups, one thing that was drilled into us pretty early on was the importance of getting crystal clear broth for the soups. The attention paid to this aspect of the soup borders on obsession.

It doesn’t matter if the stock is made from ox tails, pig’s bones or chicken and/or root vegetables, it is important to blanch them, bring to a quick boil, then cook for a long time at low to medium heat to avoid over boiling. Tending the broth requires constant skimming off all the solids and bubbles to make sure the broth is clear.

It’s a time consuming and laborious process. It’s very rewarding to get beautifully clear, sweet and tasty broth, but the process as a whole was intimidating. Being naturally lazy, we were overjoyed to learn about the Japanese method of making soup stock from kombu. Now kombu is a staple in our pantry and we hardly make stock the traditional Vietnamese way anymore.

Short description of the method: soak dry kombu in cold water (20g/l) overnight or at least 5 hrs. Heat the water until it begins to bubble, then remove the kombu. And there you have it, clear and sweet soup stock that is high in umami, but does not have any unpleasant effect of synthetic MSG.

My mom loves this method because it’s an easy way to prepare great tasty broth for vegetarian soups while avoiding MSG altogether. It’s a very convenient method because you don’t need to hover over a hot stove and still have clear broth for whatever soup dish you want to make. Actual cooking/work time is cut down significantly, which fits us lazy people perfectly.

There are more ways to extract umami from kombu, but they require immersion circulator and vacuum machine, so I’ll just add a link to this excellent post for you to read more if you are interested.

More information on kombu can be found here.

Happy cooking :)…let us know how you like the kombu broth in your Vietnamese noodle soups (phở, hủ tiếu, bún thang, etc.)


  1. I’d just add that kombu stock is very sweet and also very lean, which can be a very good thing. For bún thang we use kombu stock to boil chicken in, or vice versa, to net us a slightly fattier stock.

  2. Hello! This is so helpful…

    I’m wondering if I can use this same process for bu’n rie^u or bu’n o^’c? Can I still make this stock as the basic stock, then add some rie^u / o^’c flavor from cua / o^’c later?

  3. Hi Linh,

    Yep, definitely can use the kombu stock for bún riêu & bún ốc. The broth for the bún ốc you see in the other post was made from kombu stock & the water that used to boil the snails in. We have made bún riêu from this stock before as well.

  4. Definitely going to try this broth!! I have never heard of it and would love to have a quick way to make broth :-). Thank you!

  5. I’m going to use a kombu broth to make a leek-cauliflower velouté tonight. Will let you know how it turns out…

    Just realized that vacuum packing here refers to a method of cooking! Sounds very cool.

    • Ngan oi, I just looked up velouté…sounds yummy!

      Yeah, D is working on a post about our cooking equipment, which includes a home-made vacuum pump 🙂


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