What Is Bún Bò Huế?.

Bún bò Huế is a spicy beef and pork noodle soup from Huế, the former imperial capital in central Vietnam. The broth is built on beef and pork bones, a great deal of lemongrass, and mắm ruốc — fermented shrimp paste — then finished with annatto chilli oil that turns it red-orange. It is served with thick round rice noodles and, in a full bowl, sliced beef shank, pork hock, cubed pork blood and chả, a steamed pork sausage.

The name is literal: bún is the noodle, bò is beef, Huế is the city. It is often described as pho's spicier cousin, which undersells it — the two soups are built on different flavour logic, not different heat levels.

Where it comes from

Huế was the seat of the Nguyễn dynasty, and its cooking carries the reputation of a court city: many small dishes, careful seasoning, more chilli than the north uses. Bún bò Huế is the city's most exported dish, and the version most Americans eat has drifted from the original — bowls outside Vietnam are usually larger, meatier and slightly sweeter than what is served in Huế, where the soup is more often a breakfast than a dinner.

What makes the broth taste like that

Three things do most of the work.

• Lemongrass, bruised and simmered in quantity, gives the broth its citrus-resinous backbone. This is the flavour most people notice first.
• Mắm ruốc, fermented shrimp paste, is what people notice second without being able to name it. Used correctly it does not taste like shrimp at all; it reads as savoury depth, the same way anchovy does in a Caesar dressing. A bowl made without it tastes thin and slightly hollow, and no amount of extra beef fixes that.
• Annatto oil with chilli, added at the end, contributes colour and a rounded heat that sits on top of the broth rather than inside it.

Pork bones matter too. Beef alone gives a leaner broth; the pork hock adds the gelatine that makes the soup coat your mouth.

What comes in the bowl

A standard bowl usually carries some combination of:

• Beef shank — sliced thin, with the connective tissue left in so it stays springy rather than dry.
• Pork hock (giò heo) — a thick round of skin, fat and meat. Rich, and the piece most first-timers hesitate over.
• Chả — steamed pork sausage or crab-and-pork cake, sliced.
• Huyết — cubed congealed pork blood, mild and slightly mineral, with a texture like firm silken tofu.
• Round rice noodles, thicker than the flat noodles used in pho.

On the side: shredded cabbage or banana blossom, mint, rau răm (Vietnamese coriander), lime, sliced chilli and often a small dish of mắm ruốc to add more of the funk yourself.

How to order it

Say đặc biệt for the special, which means every meat the kitchen offers. If you would rather skip the blood cake or the hock, ask for beef only — this is an ordinary request and no one will mind. Squeeze the lime, tear the herbs in, and taste before adding chilli; the bowl is already seasoned, unlike pho.

Eat it hot. Bún bò Huế loses more than most soups as it cools, because the chilli oil that carries much of the aroma congeals.

What it is not

It is not pho with chilli added, and ordering it expecting pho is the most common way to be disappointed by a very good bowl. If you want the full comparison, read pho vs. bún bò Huế. It is also not the same as bún riêu (a tomato and crab-paste soup) or bún thịt nướng (a cold noodle salad with grilled pork), both of which share the word bún because that is simply the noodle's name.

Where to eat it in the South Bay

San Jose is one of the best places in the United States to eat this soup, and the gap between a competent bowl and a great one here is wide — the great ones taste of lemongrass and fermented depth in equal measure, and the mediocre ones taste mostly of chilli oil. Forkelo ranks the best bún bò Huế in the South Bay on evidence about the specific bowl, not the restaurant's overall rating.

If you are new to Vietnamese food more broadly, the pho ranking is the other place to start.