Basics: Kaeshi, soba and udon noodle soup or sauce base
When the weather gets warmer, we eat a lot of cold Japanese noodles: soba (buckwheat noodles), hiyamugi (thin wheat noodles), so-men (even thinner wheat noodles), Sanuki udon (thick wheat noodles- Sanuki is the name of a region famous for udon) and harusame (bean or ‘glass’ noodles). For most cold noodle dishes a salty sweet soy sauce based soup or dipping sauce called mentsuyu is used. You can buy pre-made mentsuyu concentrate, but to me most of them taste too sweet or are overwhelmed by a too-strong MSG or similar artificial tasting umami flavor. Making mentsuyu at home from scratch is not so difficult, and the difference in taste is quite worth the little extra effort.
The base of mentsuyu is a mixture of soy sauce, sugar and mirin called kaeshi (or hon-gaeshi: hon means “real” or “authentic”). It can also be used as a flavoring base for many other things. You just need good quality dark soy sauce, white sugar, and good quality mirin. It keeps for months in the refrigerator, or even in the freezer (where it will stay liquid) so I like to make as big a batch as I can afford to price-wise and fridge-space-wise.
This is similar to the Japanese essence mix, but doesn’t include the kombu seaweed or bonito. If you are a vegetarian you can use kaeshi safe in the knowledge that it’s totally vegan, and combine it with a vegetarian stock. Kaeshi also lasts a lot longer since the basic ingredients are indefinite keepers.
I’ll be talking about cold noodles and such in upcoming posts, so if you’d like to follow along, you may want to make some kaeshi to be ready.
This is a very traditional basic recipe.
Kaeshi
This makes about 6 cups.
- 4 1/4 cups (or 1 litre, the standard size for a soy sauce bottle) good quality dark soy sauce
- 3/4 cup / 180ml mirin (hon mirin, the kind with alcohol in it, is preferred)
- 3/4 cup / about 150g granulated or superfine white sugar (see notes)
Put the mirin in a pan and bring up to the boil; lower the heat and let simmer a bit to evaporate much of the alcohol content.
Add sugar and stir until melted. Add the soy sauce, and let it warm up slowly, stirring. It should never boil - once it starts barely bubbling, take it off the heat.
If any cloudy scum has accumulated on the top, skim off carefully. I t can be used right away, but is best when allowed to rest for at least a day.
Let cool and store in a glass or other non-reactive, airtight container in the refrigerator. (I keep it in preserving jars with screwtop lids.) It will keep for several months under refrigeration.
Notes
I like this to be not that sweet, but I am from the Kanto (Tokyo) area. People from the Kansai area would use 1 cup of sugar for this instead of 3/4ths. You may want to adjust the amount of sugar to your taste.
In Japan, use san-on-to- (三温糖) or cooking sugar.
If you are sugar-intolerant in any way, a heat-safe sugar substitute should work, though it’s not tested here.
Honmirin (本みりん)is regular mirin, which is a fortified sake, with alcohol content. There is also mirin cho-miryo- or mirin flavoring, which is alcohol-free mirin. I mostly just buy and use hon mirin, especially since the better quality mirins only come as hon mirin.






Cold noodles are the best!
Thank you so much for posting this recipe! I’ve been wanting to make some cold soba or somen now that it’s about 100F/38C here in Arizona and I don’t really care for the premade bottled mentsuyu out there. My grandpa used to make cold o-somen for us when we’d go visit but I never found out what he used to make his. Anyway, horray for cold noodles!
dilute with dashi
Rei, just in case, you’d dilute the kaeshi with dashi to make mentsuyu (I’ll write about that next time) I’m glad you found it helpful!
Cool
Yeah, I kinda figured that out as I was reading the recipe. It sounded way to concentrated to be used on its own, hee!
Soy Sauce/Shoyu Type
By dark soy sauce do you mean koikuchi (whats sold as regular shoyu in the US) or another type? If another type, can you recommend a particular brand? Thanks!
Dark Soy sauce?
The only Japanese Soy sauce I can find is Kikkoman naturally brewed.
Is that dark enough? Or what soy sauce should I be using? Thanks
dark soy sauce
Most of the soy sauce you’ll see sold generally is dark soy sauce. Light soy (usukuchi) is generally only available in Japanese food stores (it’s lighter in color, but actually higher in salt content). So regular Kikkoman is fine.
“especially since the
“especially since the better quality mirins only come as hon mirin.”
Hon mirin…. just means bottle of mirin. So what are you talking about?
mirin
I mean to say that the better quality mirins do not come in an alcohol-free version.
Dark Soy Sauce
Hi,
Can I use Chinese dark soy sauce? Is it the same as Jap dark soy sauce? If it is not advisable to use Chinese dark soy sauce, can you recommend a few Japanese brands of dark soy sauce that taste good? We have Japanese supermarket (Isetan) here.
Cold soba is my all time
Cold soba is my all time fav. Thanx for this recipe, came in really handy, esp now tat i’m not located where japanese food or sauces are readily available.
go figure
Wow…and here I thought it was always made with komb, bonito, and those big dried fishies…..saw my mom making it when I was growing up, and always followed the same thing…..its about the only thing I attempt to make without measuring ingredients.
jani, basic kaeshi doesn’t
jani, basic kaeshi doesn’t have the dashi ingredients you mention in it…I think because that would lessen the keeping qualties. I do have a version which has dashi ingredients (see here) but it has to be refrigerated. That’s probably closer to what your mother made.
Re: Basics: Kaeshi, soba and udon noodle soup or sauce base
You are the best. Thanks!!! NOw I can enjoy cold soba, where it's difficult to find.
Re: Basics: Kaeshi, soba and udon noodle soup or sauce base
for some reason I always seem to have problems getting the sugar to dissolve in rice vinegar or mirin. No matter how much I stir or how low or high I heat it, it just sits in the bottom of the pan.
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