At the centre of its bewilderingly long menu is pho, traditional Vietnamese noodle soup served with a choice of beef, where the integral ingredient is a broth simmered slowly for many hours to develop its rich, deep flavour.

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Now, the trading nations of Asia are responding with their own noodle soup of discriminatory deals.

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The final stop, in Ho Chi Minh City (formerly Saigon), includes chef-led cooking classes and a street-food tour -- and boundless opportunities for trying snacks such as banh mi (sandwiches), pho (spicy noodle soup), goi du du (green papaya salad) and banh xeo (rice pancakes with pork and shrimp).

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Fortunately four to five meals per day of char kwey tiaw (fried noodles in soy sauce with egg and various additions), asam laksa (Penang's famous, indescribably good curry noodle soup), rojak (fruit and veggie salad in a sweet dark shrimp paste) and much, much more, goes down a lot easier than heavier Western foods.

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As they get older they branch out, and foodies are on the lookout for the places that add a twist to old flavours, like making a particularly crispy oyster omelette (an egg omelette with tender fresh oysters) or using eel balls instead of fish balls in their wonton mee (noodle and wonton soup).

BBC: Finding a favourite hawker stall in Penang