Bun thang, the Hanoi bowl that is mostly knife work

Bun thang is the most labour-intensive bowl in Hanoi and the mildest-tasting one. Clear chicken broth, rice vermicelli, and a dozen components cut to matchstick width and arranged in segments across the top like a colour wheel.

Nothing in it is difficult to cook. The entire dish is knife work, patience and a broth that cannot hide behind chilli.

How many things go in one bowl?

Twelve is normal and twenty is not unusual, which is why the dish is rarely made at home for one. The core is chicken, gio lua pork sausage, egg omelette and dried shrimp. The cook prepares each one separately before assembling anything.

The broth underneath comes from chicken bones with dried shrimp and often dried squid, simmered long and skimmed hard. It is meant to be clear enough to read the pattern of the bowl through.

Why is everything cut so thin?

Thin cutting is the dish rather than a flourish. Every component has to be fine enough that one chopstick load picks up four or five at once. That is how the flavours are meant to arrive: together, in a mouthful, not in turns.

The cutting is also why bun thang costs more than pho, and why few households bother with it outside the holidays. An hour of shredding goes into a bowl that costs 50,000 dong, and the only shortcut available is to cut less carefully.

Is it really a Tet dish?

Bun thang began as a way of using up Tet, by the usual account. The new year table carries boiled chicken, pork sausage and omelette, and all three turn up here two days later, shredded and rearranged into something that looks nothing like leftovers.

Whether that is history or a good story, the association holds. Counters are busiest in the week after the holiday, and the Tet guide covers what else the fortnight involves — including how much of Hanoi is shut while the pot is being used up.

What is ca cuong, and will you get any?

Ca cuong is an essence from the giant water bug, and you will probably not get any. One drop on the tip of a chopstick, stirred through the bowl, was the traditional finish: a scent somewhere between pear and shrimp paste that transforms the broth.

The real thing is now rare and priced accordingly. Most kitchens use a synthetic version or leave it out entirely. Ask before the cook builds the bowl, and expect to pay extra when the answer is yes.

What does the broth actually taste of?

Chicken, faintly sweetened, with a depth that comes from dried seafood rather than from spice. Bun thang is the mildest of the Hanoi bowls by some distance, and a mouthful taken alone can read as plain until the toppings arrive with it.

The mildness is the point and the risk. A thin broth has nowhere to hide. The dish rewards a counter that has made it for thirty years and punishes one that has not, which is the rule the noodle soups guide applies across the family.

How is it different from pho ga?

Pho ga is one broth and one topping; bun thang is one broth and six. The noodles differ too: pho uses flat rice noodles, bun thang the round vermicelli that gives the dish its first name, and the broth here is lighter and sweeter.

Order pho when the broth is what you want and bun thang when the bowl is. Visitors who like one often like the other, and the two sit at opposite ends of what a Hanoi kitchen does with a chicken.

Where and when do you eat it?

Morning and midday, at a counter that cooks nothing else. Bun thang belongs to the breakfast end of the day in Hanoi, and the good addresses run out by early afternoon like everything else worth queueing for here.

A bowl runs roughly 45,000 to 70,000 dong, under three US dollars at about 26,000 dong to the dollar. That is above the city's usual noodle price, which the cheap eating guide sets out, and it buys an hour of somebody's knife work.