In terms of variety, there aren't oodles of Japanese noodles. There are only three basic strands: udon, soba and ramen.

UDON

Udon noodles came to Japan from China in the 7th century. They're made by kneading wheat flour, salt and water together (although corn flour can be used instead of wheat). Udon should be eaten on its own with little adornment. 'My favourite way to eat udon is with a clear broth base and Japanese fish cake and bean curd on top,' Akira says. 'The most traditional way is just with green onions. This is good for warming up in winter.'

At his shop, a bowl of hot udon with a simple sukiyaki beef topping costs $40. To satisfy local demand, he offers toppings such as chicken wings and char siu.

Because it uses such simple ingredients, udon is the most common household noodle in Japan - they even celebrate with Udon Day (July 2). It's eaten hot in winter, and cold in summer with a sweet soy sauce. It can be bought fresh in Japan, but some people make their own at home.

Although the texture of udon is meant to be firm, Akira says there can be exceptions. 'If you eat it braised in a clay pot or have it in Japanese hotpot [shabu shabu], then it can be softer.'

There's a type of udon called somen, which is made with the same ingredients - although oil is sometimes added - but instead of being cut into thick noodles, it's pulled into thinner strands.

The Grand Hyatt's Kaetsu restaurant offers another thin udon variation. Imported and made exclusively with wheat flour and mountain water from an area called Himi in Natohanto, chef Hiroyuki Ito says the restaurant is 'the only place in Hong Kong offering Himi udon. It won't lose its texture and get too soggy if you leave it in soup.' A bowl of Himi udon at Kaetsu costs $110. Served with shredded vegetables and seafood tempura, Australian beef or shrimp tempura it's $180.

SOBA

Soba is the only noodle indigenously Japanese. Originating from Nana, it used to be a staple of the poor until the Edo period, when the nobles adopted it. The soba is a buckwheat plant (soba-ko) that's ground into dark powder and mixed with flour. Soba is the least firm of Japanese noodles and the easiest to break. It's also the thinnest.

Generally, it's served cold. Like udon, soba is best eaten simply, with soy sauce and a little green onion or nori (dried seaweed). The basic style is zaru soba - cold soba with a tsuyu dipping sauce. Some people like it with wasabi. However, it's not uncommon in Hong Kong restaurants for soba to be accompanied by tempura or sukiyaki beef in soup.

Variations include: jenenjo-soba, which has wild yam flour; cha-soba, made with tea leaves and buckwheat; and goumugi, containing buckwheat and mugwort. The most famous sobas are from Nagano and are called shinano-soba.

En Japanese Dining offers a distinctive Okinawan soba, which actually includes no soba powder, so the colour is lighter. The restaurant ships the noodle in daily from Okinawa and even serves it stir-fried as yakisoba.

Unfortunately, Hong Kong isn't an ideal climate for making soba because it's best made at a temperature of about 15 degrees Celsius and a humidity about 40 per cent.

RAMEN

In a short time, ramen has become the most popular noodle in Japan. But its origin is also Chinese. It arrived in Japan about the time of the second world war and has become the quintessential Japanese fast food favoured by salary men, office ladies and schoolchildren.

In China, ramen is sometimes still made by hand for restaurant showmanship. However, few bother to do so in Japan since there's little difference between handmade and the machine version.

When it first arrived in Tokyo, ramen was served in a basic soy sauce soup. But as it spread, each region started embellishing, experimenting and developing its own styles and characteristics. In the colder northern climate of Hokkaido, they tend to use a richer thicker soup base, sometimes even tossing in a knob of butter. The Kyushu variety is famous as part of a long-boiled pork bone soup. Kagoshima's char siu is leaner from its use of black pigs.

Besides the common topping of roast pork, ramen can be accompanied by tempura, beef curry, seafood, bamboo shoots, sprouts, nori, negi (Japanese leeks) and eggs. However, the true test of a ramen is its soup (see soup sidebar). The first thing a true connoisseur will do is sip the soup for its flavour.

Chef Ma Wing-kwong, who has been preparing ramen at Ippei-An since 1987, says that 'the soup base is the soul of a good bowl of ramen. Mastering the perfect soup is itself an art and technique.'

As one of Hong Kong's first ramen shops, Ippei-An's signature dish is the Nagasaki ramen ($60), topped with a stir-fry of vegetables, seafood and meat. Also popular is the Tokusei ramen ($70), with stewed meat, soft tendon and a pork bone soup base simmered each day from 7am for at least five hours.

Another Japanese ramen shop, Yokozuna, serves the classic rich pork-bone Kyushu ramen for $45. Roppongi in Whampoa has a relatively newer ramen treatment: a Kansai-style ramen that's cooked, pan-fried and then added to a thick soup with seafood ($52). But if you're the supersize-type and one bowl isn't enough, then head to Causeway Bay's Ramen Alley, where six different shops offer a variety of ramen styles from across Japan.

May I have more soup?

How to choose from the four basic ramen soups

Shio (salt soup): The clearest of soups, for people who don't want a heavy base.

Shoyu (soy sauce soup): Another clear soup, first used in Tokyo when ramen was initially introduced.

Miso (soy bean paste soup): This brown soup is a Japanese speciality. It's sometimes available in a spicy form.

Tonkatsu (pork bone soup): The most popular style in Hong Kong. The rich broth is creamy white after hours of cooking.