Yuzu kosho is one of my absolute favorite Japanese ingredients. A salt-cured condiment made with yuzu citrus peel and chilies, it's at once intensely fragrant, hot and alive, a zesty accent that plants a big, fat palate-popping kiss to any dish. Yuzu kosho hails from the southern Japanese main island of Kyushu, an area that has traded with Korea and Southeast Asia for centuries, a connection that naturally produced some interesting cross-cultural influences. One of these is shochu. Another is yuzu kosho.
A few weeks ago, when I received an amazing box of fresh yuzu citrus that were grown here in New York, I thought, okay, now's my chance -- for the first time I'm going to try to make my own yuzu kosho. I did some research online and started experimenting, but nothing I did seemed right. Then I thought: Gotta call Chef Abe! The executive chef of EN Japanese Brasserie, Abe-san is a native of Fukuoka, the largest city in Kyushu, one of my favorite places in Japan. "When I was growing up in Fukuoka," Abe-san told me, "yuzu kosho was like ketchup is here in America --you can always find it on the dining table." How did his family use it? With grilled chicken and fish, hot pots, sashimi, buta jiru, you name it, he said. "In fact," added Abe-san, "my father spiked everything he ate with yuzu kosho."
In Japan, they make yuzu kosho with a chili that resembles Bird's Eye chili, which is common in Southeast Asia (I'm sure that's no accident). I had the New York State yuzu but couldn't find fresh Japanese chilies anywhere. What to do? Use jalapeños, Abe-san advised, a lovely bag of which I picked up at my farmers market in Brooklyn. (So not only is my yuzu kosho going to be for-real, it's also going to be locally sourced -- farm-to-table, baby! :)) Armed with jalapeños and yuzu peel, I headed to the EN kitchen to meet Abe-san before service, and learn how to make yuzu kosho. Here's his method, with photos:
In the quite likely event you cannot find fresh yuzu (at least in America), you can substitute it with other fragrant citrus. I think Mayer lemons would make amazing "Mayer-kosho." Abe-san also suggested limes, or a combination of lemons and limes. (Maybe throw in some grapefruit too?) The first step is to remove the seeds from the jalapeños and chop the peppers very fine. Make sure you use protective gloves or you'll burn the crap out of your hands! For the yuzu (or other citrus), Abe-san suggests grating the fruit with an oroshigane or microplane to produce zest. Another approach is to thinly peel the skin and chop it finer than the chilies. (I did it this way because I had to save and freeze the then-fresh yuzu peel a few weeks ago when I started this grand experiment.)
Abe-san said that the classic proportions for yuzu kosho are, by weight, 80% chopped chilies and 20% grated yuzu peel, and 10% of that total mixture in salt. But for the yuzu kosho with jalapeños, Abe-san adjusted the proportions to balance the pepper's fiery heat, and made his batch with 60% chopped jalapeños and 40% grated (or super-finely chopped) yuzu peel. He then added 10% of the total weight of the mixture in salt, arajio to be specific -- a fantastic, minerally Japanese sea salt that's still damp with brine. Once Abe-san got his desired proportions, he mixed the ingredients by gloved hand until they were well combines, and then put the yuzu kosho in jars. The yuzu kosho needs to cure for 1 week in the refrigerator before it's ready. Yuzu kosho will keep in the fridge for 1 month, or you can store batches in the freezer for up to 1 year. (Freeze the yuzu kosho after the week of curing in the fridge.)
I have to say, the taste of Abe-san's fresh yuzu kosho blows the doors off anything store-bought I've ever tried. By the way, while he was working, Abe-san wondered aloud what the yuzu kosho would be like if he made it with super-hot, fragrant habanero chilies. Great idea, next time... Thanks for the lesson, Abe-san!
12/10 UPDATE: I received some great comments about this post (thank you all!), so wanted to update: Nancy, you make an excellent point. As a final step you can certainly grind the yuzu kosho in a suribachi (Japanese mortar and pestle) or pass it through a food processor, if you prefer more of a paste-like consistency. Also, don't hesitate to adjust the proportions if you prefer your yuzu kosho more or less spicy, citrusy or salty. It's all good!
Regarding uses, I use yuzu kosho as my go-to condiment with simple salt-grilled chicken or fish, and also like to add a dab to soup (chicken soup), or combine with ponzu for a zesty hot pot dipping sauce. Abe-san told me he likes to add it to soy sauce as a dipping sauce with sashimi. Mess around with yuzu kosho and try it with different foods/dishes.
Brian, super cool to hear you're growing yuzu in the great state of Wisconsin! Yes, in Japan you can buy green or red yuzu kosho (I've also seen one in between, too, kinda orangey.) The green variety uses green yuzu peel and green chilies and is the most common, while the red one is made with ripe (yellow) yuzu peel and red chilies and is more rounded, and not as sharp. Both are excellent.
Here are some photos: