HANOI (Viet Nam News/Asia News Network) - Sweet, savoury and steaming hot are just some of the features of Hanoi's most esteemed bowls of pho.

My friend Duong Quang Phong, from Los Angeles, arrived in Hanoi for a trans-Vietnam tour. He asked me to join him for pho, the most famous food inside and outside of the country.

We decided to start our breakfast at 49, Bat Dan, a bustling street in Hanoi's Old Quarter.

As soon as we entered the street, we smelled the aromatic fragrance of pho from the shop, rousing our appetites. Although many years have had passed by, the shop maintained its same shape, doors, old tables and tools - particularly a long queue of diners patiently waiting for their turn, said Phong.

We joined the queue and heard curt words from the shop owner, Trinh Van Hieu, loudly asking guests about their orders and whether they wanted more or less rice noodles, or thick or light broth.

There was the familiar sound of a knife regularly chopping meat against a cutting board. Steam from big bowls of pho spiralled upward.

When our turn came, I ordered pho tai bap lan (stir-fried beef muscle), while Phong ordered tai lan (half done stir-fried beef).

The shop owner skillfully cut the beef and put it into a bowl with sliced fresh onions before scooping broth on top.

The shop is so crowded that we had to struggle to find a seat before joining the queue. After receiving our dishes, we returned to our seats in a corner of the shop.

Phong said the quality of the broth has remained the same for 20 years, when he returned to Hanoi the first time.

Whether pho is tasty or not depends on the broth and rice noodle, and here, the combination was just right.

Mr Trinh said he makes made the broth by simmering beef bone and organic spices such as ginger, cinnamon and sa sung (sand worms) from the northwestern province of Yen Bai and the port city of Hai Phong.

"My rice noodle is made from the VN10 species of rice grown in the northern provinces of Thai Bình and Nam Dinh," Mr Trinh said.

"The rice yields more powder, which makes our rice noodles whiter, softer and thinner, and helps it remain firm when it is dipped into hot water, compared with others."

We enjoy enjoyed the pho very much, although each bowl is was rather expensive at 50,000 dong to 70,000 dong (S$3.13 to S$4.39).

Despite this, locals and foreigners continue continued patiently queuing for their turn to enjoy an aromatic and tasty pho.

Phong told me that he would like to enjoy more pho at other famous shops such as Pho Thin at 13, Lo Duc Street and Pho at 10, Ly Quoc Su Street.

The next day we arrived at Pho Thin early in the morning.

We asked for two bowls of tai lan for 50,000 dong each. We did not have to wait long because there were not so many diners compared with Bat Dan.

A server brought us two big bowls of pho, which were also full of rice noodles and stir-fried beef that was very fragrant. Although the servers were not so friendly, the service was quick and the quality of the food pleased us.

The dish is fragrant and tasty because of the broth, which is greasy and quite sweet, while the tai lan is soft and sweet, too, mixed with ginger and garlic.

This helps shop owner Nguyen Trong Thin keep his trademark, which spread far and wide so that customers would never forget it.

Mr Nguyen set up his shop nearly 40 years ago.

From the onset, he tried pho at many other famous shops in the city and thought of special spices to create a unique recipe of his own.

After a year, he decided to serve pho tai aan, in which the beef is quickly stir-fried over a big fire in a large pan with fat in it. After that, the thin beef pieces are put into the pan and stirred quickly. Ginger and garlic are added to the pan before it is scooped into the bowl.

In 2009, after 30 years of business, Mr Nguyen was invited to Seoul to teach pho cooking techniques to a number of Koreans and Vietnamese working and living in South Korea who wished to open a pho shop there.

"In Seoul, I made rice noodles, and chose beef and spices to cook more than 100 bowls of pho," he said. "The food was so well loved that all the bowls were left empty."

A Korean general director of a large company told him he had never eaten such delicious food. He asked Mr Nguyen to sell his secret for making pho.

Mr Nguyen agreed.

After three months of training, several pho restaurants opened in Seoul, including Tang Restaurant, a popular place for Vietnamese and foreigners alike to come and enjoy "pho Thin".

The next day, we tasted pho at 10, Ly Quoc Su Street. When we reached the shop, a crowd of locals and foreigners had already gathered.

With prices between 40,000 dong and 50,000 dong per bowl, Phong said he could eat two bowls because the rice noodles seemed to be in smaller quantity compared with the other two shops, but the beef and broth were both excellent.

CNN has named Hanoi's pho as one of the top 10 most delicious dishes in the world.