Vietnamese dish Bun Rieu is featured in  CNN Travel's beginner’s guide to the best Asian noodles (Photo: CNN Travel)

On a summer day, we stopped at Ba Mam vermicelli restaurant at 28 Hang Voi in Hanoi’s Old Quarter. Although she is old, Ms. Mam gets up at 4am every morning to cook broth and prepares ingredients for the crab paste vermicelli bowls that she will sell from 7am to 4pm.

Ms. Man is making a bowl of Bun rieu for her customer (Photo: Thu Ha - VOV)

Quickly dripping vermicelli for customers, she told us: “Bun rieu used to be very simple, topped with only crab paste and several slices tomato. Now, in addition to crab paste, we add meat rolls, beef, tofu, and snails to every bowl of vermicelli soup. Seasoning includes monosodium glutamate and shrimp sauce, to each customer’s taste.”

While pouring broth full of red tomatoes from a pot into a bowl of vermicelli, Ms. Mam tells us that to make delicious soup, the cook must be really meticulous. Crabs are peeled and washed, finely ground and then sifted into the soup. Crab fat is stir-fried with grease, dried onion, and a little spice. The crab paste broth  must contain wine vinegar to create a characteristic sour flavor. Medium-sized vermicelli are used so that when served with the hot broth, they are chewy, not crushed. Ba Mam’s is always crowded with eaters all day.

Leaving the crab paste vermicelli restaurant, we headed to Huyen Thu restaurant at 2F Quang Trung, Hanoi. The restaurant is small and packed with customers.

Here, Conor James, a Briton, told us: “The first time when I ate Bun rieu is when one of my friends asked to try. It was amazing. The taste was so nice. A bowl of Bun rieu is served with noddle, fried tofu, some sort of crab, and spring rolls. All mix together with this kind of tomato soup, which looks really appetizing. I think I will definitely recommend it to my friends and my family when they come to visit me.”

Bun rieu are served at Huyen Thu restaurant, 2F Quang Trung, Hoan Kiem, Hanoi (Photo: Huyen Thu restaurant)

Ms. Huyen, who has run Huyen Thu restaurant for 25 years, says the crab paste soup is distinctive because of the broth’s sourness and aroma of wine vinegar. She added, “Many foreigners come here, mostly Koreans and Japanese. When they finish eating, they say something in their language that I don’t understand, raise a thumb, smile brightly and leave. Before the COVID-19 pandemic, they ate here 3 times a week.”

Finishing his soup, Conor smiles and says: “Bun rieu is culturally traditional food for Vietnam. The taste of the noodles combined with the sweet and sour flavor of crab soup make this dish really special. That must be why a lot of recommendations were given from CNN Travel for people to try Bun rieu when they came to Vietnam.”

Ms. Huyen says she is very proud that her crab paste vermicelli soup was rated one of the best noodles in Asia by CNN Travel. According to her, Bun rieu is associated with Vietnam’s traditional wet rice civilization.