Sea Urchin From A to Z: 26 Things to Know

Sometimes called 'Hedgehog of the Sea', 'Horse Dropping', or 'Red Cloud', sea urchins have evolved from being cavemen's feasts to one of the most sought-after ingredients for the world's most innovative kitchens. This A-to-Z list is a culinary and cultural journey from Japan to Norway, via Vietnam, Australia and the US, in order to answer our fascination with these spiky sea creatures and their sweet custard-like 'roe'.

A favourite ingredient with creative top chefs everywhere, sea urchins are prized all over the world, particularly in Japan, where they are auctioned at Tokyo’s main fish market. They are also popular in other regions, such as Europe, where they play a key part in several Italian pasta dishes and were the favourite food of the Spanish Surrealist painter Salvador Dalí, who apparently once ate 36 sea urchins for lunch. Fascinating creatures that feed mainly of kelp, they are believed to have been eaten in pre-historic times. Finally, sea urchins are packed with nutrients and can be eaten all year round. What are you waiting for?

A to E

Auction at Tsukuji. Like tuna (and many other sea items), sea urchins are sold at auction at Tsukiji Market in Japan. There are five sea urchin wholesalers (namely Tosui, Daitogyorui, Daichi, Marunaka and Toichi) and the sea urchins sold at this auction are not limited to those caught and processed in Japan. Middlemen – or Nakagai – are allowed to inspect sea urchins from these wholesalers from 1am and the auction starts approximately at 4-5am. Unlike the tuna auction, the Nakagai cannot outbid one another by raising price at the sea urchin auction. They raise their hand to show how much they are willing to pay at the same time. After the purchase, the Nakagai sell to their respective clients, who usually are chefs.

Bread. A typical way of eating raw sea urchins in Italy and Spain is with soft white bread. There are also a number of mind-bending chefs re-creating this bread-and-urchin combination. Joshua Skenes at Saison is known for his sea urchin Liquid Toast, which features cold sea urchin atop a grilled toast that is soaked in warm “bread sauce” (made from brown butter, egg yolk and soy sauce). Lee Tiernan at Black Axe Mangal serves salt-and-sake-preserved sea urchin on hot spongy squid ink flatbread with egg yolk and edible glitter.

Champagne. “Sea urchins pair well with vintage grower champagnes. The minerality and acidity of those champagnes uplift the richness of sea urchins”, says Sandia Chang, a California-born sea urchin lover and founder-sommelier of Kitchen Table and grower champagne bar Bubbledogs in London, “I like 2000 Benoit Lahaye and Selosse Substance and also Tarlant Cuvée Louis for non-vintage”.

Dalí. No other artist on earth is so much associated with sea urchins as Salvador Dalí. Obsessed with their natural form as well as “sedative and narcotic virtues”, the Catalonia-born surrealist artist captured sea urchins in many of his works, including The Discovery of America by Christopher Columbus (1959). He also once ate 36 sea urchins for lunch.

Ezobafun Uni. One of the two major edible species of sea urchins sold in Japan. Sometimes known as Hokkaido Aka Uni or cold water Aka Uni for its origin and colour. Ezobafun Uni are up to 5cm in shell diameter and have short spikes (5-8mm in spikes). The lobes are short, plump and bright orange. The flavour is rich and deeply sweet. (Warm water Aka Uni exists elsewhere in Japan).

F to J

Farming. Sea urchin farming takes place mainly in Japan, Korea and China and both in the sea and on shore. Usually, farming in the sea is done to re-cultivate aquaculture as a result of a significant stock depletion after fishing season. More experimental sea urchin farming takes place on shore. For example, in Okinawa, banana leaves and sugarcane leaves, which contain mineral compounds similar to those of seaweed, are used as feeds for sea urchins. There is also another on-going experiment in Okinawa to determine if sea urchins can be raised on a diet of Umibudo sea grapes. This ensures a consistent food supply and lowers costs in sea urchin farming.

Gusal. This sea urchin soup originates from Jeju Island in South Korea and can be eaten hot or cold. To make Gusal, the lobes of sea urchins are boiled with seaweed. Jeju Island is also known for Seongge-guksu, which is noodle and sea urchins in hot clear broth.

History of Consumption. There are archaeological evidences that indicate prehistoric consumption of sea urchins in New Zealand, North and South America, and that the Coast Salish had had many sea urchin feasts.

Italian Cooking. Spaghetti ai Ricci di Mare is the most famous sea urchin dish in Italian cooking. The dish originates in Sicily, where sea urchins could be found in abundance in the past (though less so nowadays due to diminishing sea algae), and is prepared by pan-frying sea urchins with olive oil, garlic and parsley and tossing in the spaghetti.

Jeju Women Divers. Also called Haenyeo, they are professional female divers who dive and catch sea products along the coasts of Jeju Island without any mechanical equipment. The history of Jeju women divers can be traced back to the Joseon Dynasty (1392-1897). Between May and July, the Haenyeo divers catch sea urchins.

K to O

Kita Murasaki Uni. The other of the two major edible species of sea urchins sold in Japan. Sometimes called Shiro Uni for its paler colour in comparison to Ezobafun Uni. Kita Murasaki Uni are up to 10cm in shell diameter and have long spikes (1.6-3cm in spikes). The lobes are long, pale yellow and noted for its lingering aftertaste. They are the type of sea urchins that can fetch up to 130,000 JPY (1000 EUR or 1100 USD) per box (400-450g).

Legs. Sea urchins do not have legs but they can move by pumping water out from their tube feet.

Molecular Gastronomy. Spanish sea urchins are caught in Costa Brava, and though much enjoyed by the local, they are better known for being molecularised by a Catalan native Ferran Adria. In 1994, Adria created The First Foam – a dish of sea urchin topped with mousse-like white bean “Foam” at El Bulli. This was the first ever usage of foam in gastronomy. It signalled the end of era for French-dominating Nouvelle Cuisine and the beginning of molecular gastronomy.

Nigiri. The common method of making sea urchin nigiri is “Battleship Shape”, or Gunkan-maki. The chef prepares it by first shaping a rice ball into an oval shape, wrapping it with a sheet of Nori seaweed and finally adding wasabi and sea urchin on top.

Omnivorous. Though the main diet for sea urchins is kelp, sea urchins are omnivorous. They feed on, for example, sea cucumbers, mussels and brittle stars. This diet, made variable by their habitats, dictates the taste of sea urchins.

P to T

Preserving. There are several methods of preserving sea urchins. The two most common are salt-cured – or Shio Uni – and preserved in seawater – or Ensui. Shio Uni can be done with salt only or salt and sake. The flavour can also be enhanced further by ageing under special conditions, but the lobes lose their shape over time and become paste-like. Ensui involves only cleaning and keeping sea urchins in sterilised saltwater solution, though certain sea urchin processors source extra deep seawater (2-300m) due to its ability to draw out the umami within the lobes. The lobes keep their shape. Most recently, the R&D team at Noma explores turning sea urchins into blocks, drying and curing them in the manner of bottarga.

Quality. The quality evaluation of sea urchins, especially in Japan, is done by looking, not by tasting. Auctioneers inspect processed box Uni focusing on flawlessness, organisation (i.e. how uniform), beautiful and consistent colour, size and scent of lobes, as well as reputation of the sea urchin processing companies. They only rely on feedbacks of taste from various sources. Auctioneers do not taste sea urchins as part of their evaluation.

Roddie Sloane. This crazy Scotsman brings sea urchins to the world’s best dinner tables. Sloane finds home in the Artic Circle on the coast of Norway and hand dives for green sea urchins in piercing icy water for chefs in the likes of René Redzepi, Magnus Nilsson and Esben Holmboe Bang. “These world’s most innovative and dynamic kitchen teams continually challenge me to find new things in the ocean”, Sloane adds. His extraordinary dive has played a major part in the global gastronomic revolution that is New Nordic cuisine.

Seasons. Contrary to beliefs, sea urchins are not necessarily best eaten in winter. The seasons for sea urchins vary from one region to another and the bans on sea urchin fishing often dictate their seasonal availability. In Japan, Ezobafun Uni and Kita Murasaki Uni are summer delicacies and are caught between March and August and between June and August respectively. The season for East Coast American Bafun Uni falls between October and May (hence filling the gap of seasonal availability for Japanese Ezobafun Uni), while West Coast Amerika-Murasaki Uni can be fished all year round but with a ban on designated dates between April and October. Sea urchins are available all year round in Chile but from various fishing locations. In Europe, sea urchins are delicacies for the wintry months.

Tasmania. Scientists encourage sea urchin fishing in Tasmania as an eco-culinary activism. Australian sea urchins cause havoc to the barrier reefs, devouring kelp and in turn depleting the number of lobsters and abalones.

U to Z

USA. Sea urchin fishing takes place on the East Coast and the West Coast of America. The East Coast catch – notably from Maine, Boston – is Bafun Uni (not to be confused with Ezobafun Uni). The West Coast catch – from Santa Barbara and Mendocino in California – is Amerika-Murasaki Uni. The sea urchin fishing industry in USA can be traced back to the late 1980s, though all of the catch would be exported to Japan.

Vietnamese Cooking. Sea urchins are a specialty in Phu Quoc, Vietnam. The local grill sea urchins in shell over charcoal fire and season the flesh with lime, salt, spring onions and crushed peanuts.

Work. Cleaning sea urchins requires a bit of work. First, you crack the shell open in half and separate the lobes from everything else. You, then, rinse the lobes in solution; discard any leftover innards and shells; and remove any excess water by resting the lobes on absorbent paper that does not cling or damage them.

XX/XY. The sex of sea urchins can be determined by looking at their lobes. The male lobes have a more vibrant colour and less water content. They tend to keep better over time. The female lobes have a paler colour and are softer and easier to melt. They deteriorate faster but are also much tastier.

Yellow Gonads. The only edible part of sea urchins is their yellow gonads, which are often referred to as 'roe' or 'lobes'. The colour of the gonads varies according to the species, the sex and the feeds of sea urchins.

Zinc. What's good about eating sea urchins, apart from their rich, custard-like taste? Sea urchin lobes are a great source of vitamins, fatty acids and zinc.

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