Raimu Kosho (Chilli and Lime Zest Paste)
I still remember the fantastic aroma and taste of my very first homemade Yuzu Koshou. For those who have never heard about this Japanese product, yuzu koshou (sometimes written “kosho”) is a slightly bitter, slightly tangy and definitely hot paste made with chilli and yuzu citrus, which gives it a unique fascinating aroma. It is used as a condiment in soups, with tempura or for example grilled meat. Personally I appreciate its scent and mixture of flavours especially in ramen soups and was of course very proud and happy my homemade version proved excellent. Unfortunately, I am unable to buy yuzu fruits here, but instead of going back to the very expensive commercial version, I decided to experiment with other citrus fruits, trying to reproduce the combination of bitter and hot flavours I am so fond of.
Lime zest was my first attempt and, even though its scent is not as strong and as complex as yuzu’s, the paste does smell beautiful and has a similar hot taste, with a slight touch of bitterness. It works perfectly in my ramen soups, giving them a refreshing kick, particularly welcome in the middle of winter. In short, I think this is a more than acceptable substitution for all those who cannot get fresh yuzu zest.
Apart from the yuzu replacement with lime, I have followed here Nancy Singleton Hachisu’s recipe from Hachisu’s Japanese Farm Food.
If you are one of those lucky people who have access to yuzu, check the homemade Yuzu Kosho recipe here:

TIP: The jar contents taste better after several days in the fridge and then keep up to one month (it can be frozen too).
You can use any chilli peppers of any colour, green one being slightly more pungent.
Preparation: 10 minutes + several days in the fridge
Ingredients (yields one 150 ml jar):
zest from two limes (chopped or grated, but make sure you don’t take the bitter white pith)
10 heaped teaspoons chopped chilli peppers (seeded or not)
2 flat tablespoons salt
Mix everything in a food processor (baby food processor is perfect here) or grind in the Japanese mortar (suribachi).
Put into a jar, cover and refrigerate.
Start eating after several days.
Raimu koshou keeps for at least a month in the fridge.
So much colour and flavour packed into a little jar of condiment, Sissi.
Thank you, A_Boleyn.
What? Home made? I never thought about making at home. You’re amazing! That color is gorgeous.
Thank you so much, Nipponnin. It takes 5 minutes and then maybe two days before you can eat it, so when I saw the recipe I had to try it. Of course if you have access to yuzu it tastes much better, but this false yuzu koshou is delicious too.
It is so nice that I can recreate this dish…I would never be able to have found yuzu but limes are always in my refrigerator. Thank you for the recipe. :_
Thank you, Karen. It’s a very original condiment. You should try it!
As inspired by your recipe, I did some googling and found mikan kosho and even natsumikan kosho. I have lots of natsumikan at the moment, given to us by my father. I think I’ll make natsumikan kosho. I will write about it when I do. Thanks for your recipe!
Hi Hiroyuki, I’m very happy I have inspired you! I’m sure natsumikan or mikan kosho is better than this lime version. Japanese citrus fruits are particularly aromatic!
Japanese chimichurri:)
The yield might be closer to 100ml – small technical issue.
I have never had chimichurri, but recently saw it on a BBC program and I remember there is garlic and parsley in it and also vinegar, so it has not got much in common with yuzu koshou. This condiment is very pure and I suppose less harsh (no vinegar): salt, chilli and zest. It might be compared to any Chinese fermented chopped fresh chillies, but it has also a slight bitterness from the zest.
I have just checked the content of my jar: it’s actually 150 ml. Thank you for this correction. I have updated the post.
Brilliant colour on this Raimu Koshou paste Sissi and I’m so happy to have a substitute for yuzu for this delightful recipe — lime is abundant here 😉 and this simple combination of elements is right up my alley. I don’t know why I feel the urge to add a small pinch of sugar to the mixture (tangy, hot, salty, sweet – woo-hoo!!! 🙂 ) but I will try your version first. Have a beautiful weekend my friend.
Thank you so much, Kelly. Sugar sounds like a great idea of course! I also love hot and sweet mixture of flavours.
I’ve not heard of this unique condiment Sissi, it is quite a beautiful bright green colour. I’m not sure I would enjoy the bitterness, but you did say slightly so I’m guessing it isn’t overwhelming. I’m quite curious how it would taste in ramen soup, I shall be on the lookout for it when we dine again at a Japanese place.
Thanks a lot, Eva. The bitterness is really slight: it comes from the zest which has always a slightly bitter side. On the other hand, I still remember when I tasted this condiment for the first time I didn’t really know how I might use it… Now I know it is perfect with filling and/or greasy or heavy dishes but also on grilled meats. I don’t know if they serve it in restaurants though.
wonderful recipe, thank you, I will definitely try it. I always wonder wether it would be a good idea to fake the yuzu zestes by using tangerine peel mixed with some pomelo and lime peel. After reading Hiroyuki’s response I think it may work.
Thank you, Kiki. I hope you will experiment too. It’s to simple and so delicious!
WOW! I can’t wait to be able to find some fresh chiles around here. This looks like a “must have” condiment and I’m sure it would be awesome in SO many dishes. I wonder – do you think this would work with roasted, frozen chile? It might not last a month, but it sounds like it might work with some NM chile I have in the freezer. I’m sure I could use it up in a couple of weeks by scooping a teaspoon or two on eggs, in vegetable dishes or soups. What do you think Sissi?
Thank you so much, MJ. I was really surprised how citrus zest combined with chilli creates a unique result (it is completely different from all the spicy condiments I have ever made and between jellies, chilli oils and pastes I prepare quite a lot of these!). I have to buy imported chillies anyway (I rarely see Spanish chillies but usually they come from Turkey or Morocco, from green houses… so somehow I lose the track of its seasonality). Do try it with frozen ones (but maybe you won’t be able to keep it for a long time afterwards…). Good luck!
Hey, This post is looking so good and Amazing! A very well made post with beautiful pictures. I’ve bookmarked this special recipe of yours and would love to give it a shot soon. Thanks for sharing your well prepared and presented recipes. Shall look forward to your next post.
Have a wonderful week ahead. Take care.
Thanks & Regards, Sonia!!!
Thank you, Sonia.
I love that this is homemade and has so much flavor happening! It has to smell extra great too!
Thank you, Pamela.
I am not sure I can find yuzu here but limes can be found in abundance. The color is amazing and I am sure the taste is equally great!
Thanks a lot, Katerina. Yes, yuzu is difficult to find in Europe (here impossible), so this is why I started to look for other citrus options. I’m sure you have lots of aromatic citrus fruits in Greece.
Screw the meat – I’d put this on sandwiches Sissi. I can just imagine the flavours. When I saw the first photo I had an overwhelming urge to put it on pizza but then I had to tell myself that perhaps lime on pizza might be a bit weird, but hey – there’s more weird things I’m sure. French people put eggs and potato on them, why shouldn’t I put lime (and yummy chilli) paste on it?
Haha! Thank you so much, Charles. I actually put it more often in ramen (I make ramen stock every week now!). Even though my stock (chicken) is not as heavy as pork bone stock (tonkotsu), this condiment makes everything so lighter… I think you can put it in every dish, though I discovered that the zest doesn’t go well with everything.