Bun Bo Hue (Spicy Lemongrass Beef Noodle Soup)
A bold, fragrant Central Vietnamese noodle soup: a deeply beefy broth perfumed with lemongrass and fermented shrimp paste, finished with a brick-red chili-lemongrass satay oil and ladled over thick, chewy rice noodles with tender sliced beef shank.
- Prep
- 50 min
- Cook
- 2 hr 50 min
- Wait
- 30 min
- Total
- 4 hr 10 min
- Makes
- 6 large bowls (about 3.5 L / 3.7 qt of broth plus noodles and toppings)
Steps
Before you start
- Buy shrimp paste labeled 'mam ruoc' or 'mam tom' for Hue-style cooking. It is purple-gray and very pungent; the fermented shrimp paste in a jar for Thai cooking is not the same. Open a window and turn on the vent fan.
- You need a 10–12 quart (10–12 L) stockpot. Smaller pots will boil over and make it hard to skim.
- Read the whole recipe first. The shrimp paste must rest for 30 minutes, and the shank is removed from the broth partway through.
- Look for thick, round rice noodles labeled 'bun bo Hue' or 'bun to' (about 3 mm thick). Thin vermicelli turns mushy in this hearty soup.
Dissolve the shrimp paste
- In a medium bowl, whisk the shrimp paste into 1 cup (240 ml) warm water until no lumps remain.
- Set aside for 30 minutes without stirring so the sediment settles to the bottom.
- Meanwhile, move on to the next step.
+ Show details− Hide details
Ready when: A pinkish-gray liquid on top with a thick sludge on the bottom
Tip: Do not stir or shake the bowl after it settles. The sludge makes the broth cloudy and gritty.
Parboil the bones and shank
- Put the beef shank, beef bones and pork bones in the stockpot and cover with about 3 quarts (3 L) cold water.
- Bring to a boil over high heat and boil hard for 10 minutes.
- Scum will rise and turn the water gray-brown.
- Drain into the sink, then rinse each bone and the shank under running water, scrubbing off any dark bits.
- Scrub the pot clean.
+ Show details− Hide details
Ready when: Thick gray scum floats on the surface and the water looks murky
Tip: This step is what gives you a clean, clear broth. Do not skip it.
Char the aromatics
- Heat a dry skillet over medium-high heat.
- Place the onion halves cut side down and the smashed ginger in the pan.
- Cook 6–8 minutes, turning the ginger once, until the onion is deeply browned on the cut side and the ginger is blackened in spots and fragrant.
+ Show details− Hide details
Ready when: Onion cut sides are dark brown with some black spots; ginger smells sweet and smoky
Tip: Open a window. The charring is smoky, but it adds a roasted depth to the broth.
Simmer the broth
- Return the clean bones and shank to the clean pot.
- Add 4.5 L (4¾ quarts) cold water, the charred onion and ginger, smashed lemongrass, sugar and salt.
- Bring to a boil over high heat, then immediately reduce to low so the surface barely bubbles.
- Partly cover and simmer for 1 hour 30 minutes, skimming any foam in the first 20 minutes.
- At 1 hour 30 minutes, test the shank by piercing it with a knife: it should slide in with slight resistance.
- Lift the shank out with tongs.
+ Show details− Hide details
Ready when: Shank is tender when a knife slips in easily with slight resistance (about 195°F / 90°C inside); broth is lightly golden
Tip: Keep the simmer gentle. A hard boil makes the broth cloudy and the shank stringy.
Cool and slice the shank
- Plunge the hot shank into a bowl of cold water for 10 minutes.
- This stops the cooking and keeps the surface from darkening and drying.
- Pat dry, then slice against the grain into pieces ⅛ inch (3 mm) thick.
- Cover the slices with plastic wrap.
- Slice the cha lua, if using.
+ Show details− Hide details
Ready when: Shank feels firm and cool, and slices hold together without shredding
Tip: Slice against the grain (across the visible muscle fibers) so each piece is tender.
Make the chili satay
- While the bones keep simmering, heat the oil and annatto seeds in a skillet over medium-low heat for 2–3 minutes until the oil turns deep orange-red.
- Scoop out and discard the seeds.
- Add the shallots, garlic and minced lemongrass and cook, stirring, 4 minutes until softened and golden at the edges.
- Stir in the chili flakes and cook 30 seconds more.
- Remove from the heat.
+ Show details− Hide details
Ready when: Oil is bright red-orange and the mixture smells fragrant, not burnt
Tip: Chili flakes burn in seconds. Take the pan off the heat as soon as they sizzle and darken slightly.
Finish simmering the bones
- Return the pot to a low simmer with the bones still in it (the shank is out).
- Continue simmering, partly covered, for 40 more minutes to extract more flavor from the bones.
+ Show details− Hide details
Ready when: Broth tastes rich and beefy, and the meat is falling off the pork bones (pork reads at least 145°F / 63°C)
Season and strain
- Carefully pour the clear shrimp paste liquid into the broth, stopping before the sludge at the bottom; discard the sludge.
- Stir in the fish sauce and about three-quarters of the chili satay.
- Simmer 15 minutes.
- Remove the bones with tongs and strain the broth through a fine-mesh strainer into a clean pot.
- Taste and add salt or fish sauce a little at a time; the broth should be savory, slightly sweet, spicy and pungent.
- Keep hot over low heat.
+ Show details− Hide details
Ready when: Broth is a vibrant orange-red with a savory aroma and no raw shrimp-paste smell
Tip: The broth should taste slightly too strong on its own, because the noodles will dilute it in the bowl.
Cook the noodles
- Bring a 5-quart (5 L) pot of water to a rolling boil over high heat.
- Cook the noodles according to package directions, usually 8–10 minutes, stirring once or twice.
- Drain and rinse under cold running water, tossing with your hands, until the noodles are no longer sticky.
- Drain well.
+ Show details− Hide details
Ready when: Noodles are chewy but tender with no hard white center when you bite one
Tip: Cook the noodles right before serving. They become gummy if left to sit.
Heat the cha lua
- If using cha lua, bring the strained broth to a steady simmer over medium heat.
- Drop in the sliced cha lua and heat for 2–3 minutes.
- Lift out with a slotted spoon and check a thick slice with an instant-read thermometer.
+ Show details− Hide details
Ready when: Center of the thickest slice reads at least 160°F (71°C) and the slices are hot and slightly plump
Tip: Cha lua is sold cooked, but reheating it to 160°F (71°C) makes it safe to eat.
Assemble the bowls
- Divide the noodles among 6 deep bowls.
- Top each with sliced shank, a few slices of hot cha lua, some cabbage, bean sprouts, red onion, scallions and cilantro.
- Return the broth to a full simmer, then ladle about 1½ cups (350 ml) of boiling-hot broth over each bowl.
- Serve right away with lime wedges, sliced Thai chilies and the remaining chili satay on the side.
+ Show details− Hide details
Ready when: The broth is steaming and warms the beef slices through
Tip: Make sure the broth is at a full simmer when you ladle it so the raw cabbage and sprouts soften slightly.
Good to know
Tips
- Do not skip parboiling the bones. It removes impurities that make the broth cloudy and funky-tasting.
- Add shrimp paste in stages. Brands vary a lot in saltiness, so taste after the first half of the liquid and adjust the fish sauce accordingly.
- Serve with extra satay on the side so each person controls the heat. The satay oil also keeps in the fridge for a week.
- For a traditional touch, add a little shredded banana blossom or Vietnamese herbs such as perilla and rau ram if you have them.
Make ahead
The broth and satay can be made up to 3 days ahead. Cool the broth quickly, refrigerate, and lift off the solidified fat if you like. Slice the shank and keep it covered in the fridge. Reheat the broth to a full simmer before serving and cook the noodles fresh.
Storage & reheating
Room temperature: no more than 2 hours. Fridge: store broth, beef, noodles and toppings separately in airtight containers for up to 4 days (noodles up to 2 days). Freezer: broth freezes well for up to 3 months; thaw overnight in the fridge. Reheat broth on the stove to a full boil; dip cold noodles in hot water for 20 seconds before assembling. Reheat leftover cha lua to 160°F (71°C).
Substitutions
- Vietnamese shrimp paste (mam ruoc) → 2 tablespoons extra fish sauce plus 1 teaspoon miso. This loses the signature funk of Hue-style broth but gives a savory, fermented depth. Use only if you cannot find mam ruoc.
- annatto seeds → 1 tablespoon sweet paprika. Stir the paprika into the warm oil off the heat for color; the flavor is slightly different but still good.
- coarse Korean chili flakes (gochugaru) or Vietnamese chili powder → 1 tablespoon cayenne pepper plus 1 tablespoon sweet paprika. Cayenne is hotter than gochugaru, so use less if you prefer a milder bowl.
- pork neck bones → pork hock or extra beef bones. Pork hock gives a more gelatinous broth. Extra beef bones give a cleaner beef flavor.