What you always wanted to know about uni or sea urchin

An acquired taste to some and adored by many, uni is an indulgent delicacy that enjoys cult status. Annabel Tan and Sara Yap dive into what makes this ocean treat so appealing and highlight some of the most creative ways chefs are serving it.

Sea urchins are a prime example of why one should never judge a book by its cover. These spiny, spherical echinoderms (marine animals related to starfish and sea cucumbers) may have a prickly exterior, but their hard shells conceal a highly prized treasure. The edible gonads of the urchin – yellow-gold slivers of delicately sweet, buttery and slightly briny decadence – are a coveted culinary treat in many parts of the world. This is especially true in Japan, which accounts for around 80 per cent of global uni consumption.

Sometimes also called sea urchin roe (though it is more accurately the reproductive organ that produces roe), uni is typically enjoyed raw to appreciate its creaminess and distinct oceanic flavour. It can be eaten in a myriad of ways, most commonly in sushi, Japanese rice bowls, sashimi- style, or mixed into pasta to create a creamy, umami sauce.

Beyond its bold taste, it is also a good source of protein, fibre, vitamins A and E, and essential minerals. Similar to fatty fish like salmon, uni is high in omega-3 fatty acids, which can help lower blood pressure and reduce the risk of abnormal heart rhythm.

Find your flavour

There are about 950 known species of sea urchin that exist across a wide range of depth zones in the world’s oceans, of which about 180 are in the waters surrounding Japan. However, just 18 species (usually pinkish- red in colour) are edible and harvested for consumption. The traditional harvesting regions are Japan, Chile and the US, with other countries like Canada, Russia and Peru also supplying to the global market.

Generally, uni is packed with sugar, salt and amino acids, resulting in an irresistible trifecta of umami, saltiness and sweetness. But, for uni lovers, it is the nuances in each variety that set them apart. Like oysters, the flavour of uni varies depending on its species, the region it was harvested and what the uni feeds on, as well as its freshness. Fresh uni should have a firm custard-like texture that holds its shape but still melts in the mouth.

Some of the most common varieties of uni are Murasaki, which has a yellow hue and clean flavour; Aka, which carries notes of bitterness; and Bafun, a vibrant orange- hued, sweeter option. Ultimately, experts say the best type of uni comes down to personal preference.

Restaurateur-chef Beppe De Vito, who runs the IlLido Group in Singapore, finds that uni from Europe tends to be saltier, while its Japanese counterpart is “smoother and gentler in terms of texture and taste”.

This sentiment is echoed by Japanese-born Australian celebrity chef Tetsuya Wakuda, who uses Hokkaido sea urchin in his food at one-Michelin-starred Waku Ghin in Singapore. “The sea urchin we use is unique due to the clean waters that it lives in and because of the kombu, or kelp, that it feeds on. This results in a flavour that is creamy, sweet, and has a unique seaweed-like taste without an overpowering ironised aftertaste,” he remarks. “The texture is very delicate, and it melts in the mouth.”

Given that it is essential to enjoy uni as fresh as possible – more so than any other seafood – proximity also plays a part in the varieties chefs choose to serve. At the two-Michelin-starred Twins Garden in Moscow, Russia, chef twins Ivan and Sergey Berezutskiy showcase uni from two different regions of Russia: Murmansk and the Russian Far East. “As the Russian Far East sea urchin comes from almost the same location as the Japanese ones, they are quite similar in flavour, whereas Murmansk sea urchin is brighter, deeper and has a very special taste due to the exceptionally cold sea in the northern region,” say the brothers.

Fruit of Labour

Fresh, quality uni does come at a premium price, given the difficult harvesting process and minimal yield that each bristly orb contains – one sea urchin typically only has five gonads. In the US, divers have to go as deep as 24m down into the water and pluck the urchins by hand from the ocean bed.

In Jeju island, South Korea, a similar feat is taken on by women who are trained from a young age to dive in frigid water and hold their breath for over three minutes at a time. These haenyeo, meaning “sea women” in Korean, plunge up to 30m with minimal gear to harvest sea urchins and other sea life.

Over in Japan’s Shakotan Peninsula, fishermen remain in their boats for long periods, searching for urchins with a claw-like tool. “Good quality sea urchins are hand-harvested in cold waters and are available only in short periods of time during each season. This rarity makes them more appealing,” explains Wakuda, who also runs Tetsuya’s in Sydney, Australia.

The best season for Japanese uni is said to be from September to the end of April, but also varies according to the species. In Spain, some believe that the optimal time to obtain sea urchins is during winter as the Mediterranean Sea level is lower, making it easier for divers to reach the coveted sea creatures – though not without braving the cold.

The hard work does not stop there. Once harvested, the uni has to be thoroughly cleaned and repackaged – typically arranged in neat rows in a box. There is also ensui uni, which is packed in saltwater without any preservatives or chemicals. Though not as beautifully presented as boxed uni, ensui uni better retains its natural taste and texture, offering the closest experience to cracking open live sea urchins by the sea. A few home-grown online grocers offer both boxed and ensui uni for home delivery, such as Zairyo and Shiki, both of which specialise in Japanese produce.

In addition to the labour-intensive fishing, environmental factors also come into play. Japan, for one, has been hit by several natural disasters that devastate marine life. Most recently, a series of red tides – a phenomenon caused by harmful algae blooms producing toxins – in Hokkaido ravaged approximately 2,300 tons of sea urchins late last year, driving up uni prices.

Zairyo co-founder Amanda Tan shares that the retail price of Japanese uni on her website was about $140 for 250g when she first started the platform eight years ago. Today, due to the supply crunch, the same type of uni will set one back between $200 and $368. Based on her conversations with the uni factories and sellers at Toyosu Market in Tokyo, Japan, Tan says uni prices are unlikely to drop – at least not for the next two years – until the habitat recovers.

Gourmet Gold

Arguably, the best way to savour uni is live, fresh out of its shell and sans supplementary ingredients. First, cut and pry open the sea urchin’s prickly shell, then pour out the black substance, which is a mix of viscera and partially digested food. Gently rinse with salt water then use a spoon to scoop out the soft lobes of uni.

While this purist method is unbeatable, enjoying uni in modern restaurants can be an exciting epicurean experience. One of the first in recent history was a ground-breaking dish by Spanish culinary superstar Ferran Adrià in 1994. Hailed as one of the best chefs in the world, Adrià created a dish of cold white bean foam served atop a whole sea urchin during his stint at the now-defunct elBulli. That dish was also his first foam creation and propelled him to stardom as the pioneer of molecular gastronomy.

These days, many chefs around the world are also delighting diners with innovative and unexpected uni dishes. New York tapas bar El Quinto Pino is famed for its sea urchin panini – a sandwich filled with uni mixed with butter and spicy mustard oil – while a signature dish at Hong Kong’s two-Michelin-starred French restaurant, Amber, is Aka uni with cauliflower, lobster jello and caviar.

In the gastronomic paradise of Singapore, Waku Ghin is known for its iconic and extremely photogenic dish of marinated Botan shrimp with seasonal Bafun or Murasaki uni and caviar. Much detail goes into the preparation of this indulgent concoction: The uni is first stored in the chiller between 0 and 2 deg C to preserve its freshness, before being lightly seasoned with Japanese soy and mirin. As for the shrimp, it is marinated with salt, pepper, olive oil, shallots and tarragon.

The uni and shrimp are then placed into a sea urchin shell and bedecked with generous lashings of Gold Oscietra caviar. “The flavour of the whole dish comes together and is well-balanced without overpowering any of the ingredients. It is simple yet sophisticated,” says Wakuda.

This idea of keeping things simple in contemporary uni dishes is shared by Ayo Adeyemi, head chef of award-winning Tippling Club, a modern gastronomic institution here. “The star of the show should be the uni itself. It’s a very delicate ingredient and flavour – it should be respected and not overcomplicated,” he says. “With this in mind, we always focus on simple flavours and dishes, such as pairing it with eggs or white asparagus.”

Also extremely selective about when they use uni, Tippling Club only serves it once or twice a year at the peak of the season in Japan. One of Adeyemi’s creations is the Bafun Uni Omelette, comprising a bed of soft, lightly scrambled Kagoshima eggs, topped with salmon roe, Bafun uni from Hokkaido and a wasabi Béarnaise. The dish is then lightly grilled before being garnished with fresh hanaho flowers.

When it comes to designing uni dishes, chefs often use the ingredient to incorporate a layer of richness into the food. Chef Akane Eno serves a seasonal dish of roe-filled spear squid topped with fresh uni at her Japanese restaurant, Ichigo Ichie. “Roe-filled spear squid is seasonal and delicious but it lacks the creamy liver that the surume squid has. I wanted to supplement the squid by adding some velvety uni to add a rich dimension to the dish,” she says.

Uni is used in a similar way for a special four-hands collaboration between two Sheraton Towers Hotel restaurants. As part of an exquisite eight-course dinner available till May 1 at Li Bai Cantonese Restaurant, executive Chinese chef Chung Yiu Ming joined forces with chef Akihiro Maetomo of Maetomo Japanese cuisine Kaiseki & Sushi to create an egg white crepe dumpling filled with Alaskan king crab, Hokkaido scallop and okra, dressed with Hokkaido sea urchin and salmon roe.

“The egg crepe dumpling is a popular Li Bai dish originally filled with bird’s nest and when chef Chung shared it with me, we thought about changing the ingredients and adding textural contrast to this dish. By adding sea urchin to the sauce, it lends a creaminess and complements the seafood within the dumpling,” says Maetomo. “I enjoy using uni as it is a popular premium ingredient with many customers – especially Hokkaido Uni, which is rich in flavour. The vivid colour also enhances the appearance of a dish.”

This story first appeared in the April 2022 issue of Prestige Singapore.