- Kosho is most commonly created from yuzu zest and chilli, though more modern interpretations utilise a variety of fruits. It was made in Japanese homes until the 1950s when mass-produced versions came to the market. Last year, it was added to Waitrose's revamped Cooks' Ingredients range.
- Kosho is traditionally used in savoury dishes, but it can also be found in sweet ones. It has appeared in KitKats in Japan, while in the US chef Frederico Ribeiro includes yuzu kosho in his much-touted Taiwanese pineapple linzer cookies, served at New York teahouse Té Company.
- The world's third most popular cuisine is Japanese, according to a 2019 international YouGov study of more than 25,000 people in 24 countries. Japanese food is liked by 57% of people in the UK.
Japanese food fans may already have heard of yuzu kosho. Traditionally served on the side of a bowl of ramen, stirred into miso soup, or brushed over grilled meat or fish, this punchy, fermented paste, which brings together yuzu, chilli and salt, is regularly referenced on the menus of Japanese restaurants.
But unlike other Japanese ingredients such as miso or wasabi, which are used widely by chefs cooking different cuisines, this curious condiment has remained faithful to its roots and not ventured far outside of its Japanese cooking circle – until now.
Perusing the menus of restaurants that would never describe themselves as Japanese, including Flor, The Oystermen Seafood Bar & Kitchen and The Coal Rooms in London, you'll find mention of kosho, both the yuzu and non-yuzu kind.
At Flor, for example, chef James Lowe daubs orange yuzu kosho onto scarlet prawns; kosho comes with oysters and spicy buffalo sauce at The Oystermen, while at The Coal Rooms it spices up an avocado and tomato sandwich.
The fact that kosho is appearing more widely on menus both intrigues and excites Ross Shonhan, creator of Japanese-inspired restaurants Bone Daddies, Flesh & Buns and Shackfuyu.
The Australian chef-restaurateur, who worked at Nobu in Dallas and Zuma in London before branching out on his own, has been cooking with kosho for over 15 years. In that time, he has experimented widely with two of the paste's three elements – citrus and chilli – to create his own variations, as well as serving yuzu kosho in more innovative ways.
“I've used fresh sudachi peel with jalapenos and grapefruit with serrano red chilli,” he says. “Kosho is incredibly versatile and as soon as you play with different citrus and chillis, it opens it up. It's great on grilled prawns, with fish and meat.”
Shonhan welcomes kosho's wider use, particularly because it will help introduce the ingredient to more people.
“It's interesting that now you're starting to see more chefs who historically do modern British even making their own koshos and using it in similar ways that the Japanese do. For years we've had customers asking what it is in our restaurants, so it's great to raise awareness of it in this way.”
Ross Shonhan, founder of Bone Daddies Group, describes yuzu kosho mayonnaise served with fried chicken and tenderstem broccoli: “We mix pre-made yuzu kosho into mayonnaise with a bit of ponzu dressing to lighten it up a little. We use a small jar of yuzu kosho with 700g of mayonnaise. Yuzu kosho is quite salty and citrussy, which is why it works well with something fatty like mayonnaise. We started serving the mayo with blanched, chilled broccoli, but so many people started requesting it with the fried chicken that we added it to the menu so they'd get it automatically. The yuzu kosho mayonnaise together with the seasoning we put on the chicken is a bit salty for me, but customers love it. Once you mix yuzu kosho into mayonnaise you can use it in anything. It's great with chicken katsu, in sandwiches and works well with sushi. At Shackfuyu, we use it in a prawn tempura roll. It's been one of my favourite ingredients for a long time and it's good know there's growing interest in it.”
Byron Fini, head chef at Peg, London, makes kumquat kosho to accompany grilled white asparagus: “Kosho is a great way to preserve what we can in a short period of time, so we use whatever we have available that's suitable. We made massive amounts of the kumquat one, which we mainly utilise during asparagus season. To make it, we split a whole kumquat in half, remove the seeds and macerate it with red chilli and salt. Even after the short fermentation it has it is very vibrant. Kumquat is very pithy in flavour and naturally sweet as well. With the chillis we used, which were quite mild, it was well balanced: tart, sweet and a bit hot. It was also quite fluid due to the kumquat, so it made a good sauce. We served the kumquat kosho as a base for grilled white asparagus brushed with tare (a yakitori sauce). Kosho adds a real high note to our food and a different flavour profile. We use a lemon and jalapeno one with grilled chicken thighs.”
John Javier, executive chef at Pachamama East, serves yuzu kosho with a starter of lamb anticuchos: “Anticuchos are a huge part of Peruvian cuisine. At Pachamama East, being Chifa inspired, we dice and skewer lamb rump and marinate it in doubanjiang – a traditional Chinese fermented chilli and soybean paste. After the anticuchos are grilled, we serve it alongside yuzu kosho. This dish really sums up the massive influence of Asian culture on the history and cuisine of Peru. Yuzu kosho is an amazing ingredient and there’s nothing really quite like it. It’s spicy, aromatic, salty, sweet and sour. There are also countless ways we could make or apply yuzu kosho to other dishes, but this is the only dish at Pachamama East where it’s represented as we try to focus more on Chinese ingredients.”