With between ten and fifteen thousand sushi shops in Tokyo alone, sushi has been called the most popular food in Japan. These small, flavorful bites, each offering new tastes and textures, have become a worldwide sensation. Sushi is a fascinating national food from a generally healthy, low-fat, high-protein cuisine in which nothing is wasted.

Sushi does not necessarily involve raw fish. Su can mean "vinegar;" or, in its Chinese reading, ju or "long life." The shi is most often the Chinese reading of the Japanese character tsuka, which can mean "to control" or "to arrange."

Mind you, "arranging for long life" would not be the proper translation of sushi. Failing an adequate interpretation, the most applicable meaning might be vinegared rice - or items served on or in vinegared rice.

However, as sushi has grown in popularity around the globe, those items have, more often than not, tended to be raw fish. And why not? Eating seafood rich in Omega-3 fatty acids at least twice a week benefits the hearts of healthy people, as well as those at high risk of cardiovascular disease.

Japan, an archipelago surrounded by seas, is a great fish-eating nation. Squid, octopus, and the many varieties of ocean fish are enjoyed in enormous quantities. Seaweed, various shellfish, sea urchin, shrimp, and prawn are all eaten, as well - but the national favorites are those meaty fish found in the Pacific: tuna, mackerel, bonito, and sea bream (aka "red snapper").

The Japanese broil, steam, grill, fry, and dry fish. Among all these, however, the most popular method of presentation is fresh, or raw. Fresh seafood is served in two ways.

Sliced and appropriately decorated, served in a bowl or on a dish, fresh seafood is called sashimi: slices of raw fish, served without rice. This is often the first course of a typical Japanese meal.

When fresh seafood covers fingerfuls of rice and is a meal in itself, this is modern sushi: visually appealing, flavorful and nutritious.

The oldest form, Nare-zushi, dates back two-thousand years. As is the case with so many beloved foods, its beginnings were somewhat unappetizing. Rice was packed around uncut fillets, and the combination was preserved for months. The rice was then thrown away, and the aging flesh, eaten. One of these early pressed sushi, funa-zushi, or preserved carp, is still enjoyed in Japan today and is most closely associated with Shiga Prefecture. Toyama has masu-zushi made with trout, and Kyoto in the summertime has ayu-zushi, fresh fillets of the small, salmon-like ayu on rice.

During the Muromachi period (1336-1573), the twelfth-generation emperor, Keiko, was served raw clams dressed with vinegar - an ingredient with antibacterial properties, and helpful when working with raw fish. The emperor liked them so much that he made the inventor, Mutukari no Mikoto, his head chef. The basic definition of sushi evolved to become a combination of raw fish and vinegared rice, consumed together. This was nama-nare-zushi, partially fermented.

By the mid-eighteenth century, sushi was being crafted in bamboo molds and sold as shapely bite-size edibles in Tokyo.

The contemporary sushi, an early form of fast food, was invented by sushi-stall operator Hanaya Yohei (1799-1858). It is believed that he wanted to come up with a way to quickly feed Kabuki theatergoers, who might be famished, but not want to miss the beginning of the third act. Yohei came up with an assortment of small morsels of freshest raw fish and seafood, pressed into cooked rice, lightly seasoned with vinegar. It could be prepared quickly, with no fermenting, no pressing into molds, and no waiting. It could be eaten with the hands, eliminating utensils altogether. Originally, this sushi was known as Edomae zushi because it used freshly-caught fish in Tokyo Bay (Tokyo was formerly known as "Edo").

The fish used in modern sushi no longer comes from Tokyo Bay. Only sushi-grade fish is used for sushi and sashimi. "Sushi grade" is an industry term for high-quality seafood, properly handled and processed, and suitable for consumption as raw. Nonetheless, sushi in Japan is still formally known as Edomae nigirizushi.

More generally, it may be called oshi-zushi - freshly cooked rice, tossed with a rice vinegar dressing, cooled, then pressed with the freshest and best ingredients available.

There are many variations. A square of seaweed might be swiftly coated with rice, something put in the middle, wasabi (Japanese horseradish) added, and the whole, rolled into a long cylinder that is then cut into pieces or eaten as is. If pickled dried gourd is used inside, the result is called nori maki; if cucumber, kappa maki; if strips of fresh tuna, tekka maki; if omelet and seafood mixed, datè maki, and so on. There's even a bit of thick, sweet omelet on rice called tamago-yaki.

The seaweed might be rolled to make an ice-cream-cone-shaped sushi called temaki-zushi. Or, vinegared rice can be packed into a bag of fried tofu, with the result called inari-zushi. Or, the rice is wrapped in dwarf bamboo leave and called sasa maki-zushi. Or, a favorite to make at home, seafood is shredded over a bowlful of vinegared rice, and the dish is called chirashi-zushi.

A delight to the eye as well as a revelation to the tongue, sushi is an engrossing culinary happening that those who have tasted will not soon forget!

Further reading

• The Zen of Fish: The Story of Sushi, from Samurai to Supermarket
  Trevor Corson
  HarperCollins (2007)
  Find the book on Amazon