Spicy Beef Noodle Soup (Bún Bò Huế)

Ingredients

Broth

• 1 kg (2¼ lb) beef shank, whole or in large pieces
• 750 g (1⅔ lb) beef or pork bones
• 3.5 litres (14 cups) water
• 3 stalks lemongrass, bruised, plus 2 stalks finely minced
• 1 onion, halved
• 1 small piece ginger, about 5 cm (2 in), smashed
• 1 tbsp salt
• 2 tbsp fish sauce, plus more to taste
• 1 tbsp sugar
• 1 tsp shrimp paste (mam ruoc), dissolved in 120 ml (½ cup) water, then strained

Chilli oil

• 3 tbsp neutral oil
• 3 shallots, minced
• 2 tbsp chilli flakes or 1½ tbsp chilli paste
• 1 tsp annatto seeds or paprika, for colour

To serve

• 500 g (1 lb) thick round rice noodles (bún), cooked (or the thickest dried rice noodles you can find)
• Shredded cabbage, bean sprouts, banana blossom (optional) or herbs such as mint and cilantro
• Lime wedges and sliced chillies

Steps

1. Cover the bones and shank with cold water, boil hard for 5 minutes, then drain and rinse well to keep the broth clear.
2. Return to the clean pot with the 3.5 litres of fresh water, bruised lemongrass, onion, ginger and salt. Bring to a boil, then reduce to a bare simmer.
3. Cook uncovered for 1 hour, skimming foam. Lift out the shank when a skewer goes in easily, after about 1½ hours total, and plunge it into cold water for 5 minutes so it stays moist.
4. Return the pot to simmer for another 1½ hours with the bones, until the broth tastes beefy and slightly sweet.
5. For the chilli oil, warm the oil over medium-low heat. Fry the shallots and the minced lemongrass for 2 minutes until fragrant, then add the chilli and annatto and cook 1 minute until the oil turns deep red. Do not let it scorch.
6. Strain the broth into a clean pot. Stir in the chilli oil, fish sauce, sugar and shrimp paste. Taste; it should be savoury, citrusy and warmly spicy.
7. Slice the cooled shank thinly against the grain.
8. Bring the broth to a rolling simmer. Divide noodles among bowls, top with sliced beef, and ladle the hot broth over. Serve with the cabbage, sprouts, herbs, lime and chillies.

Notes

• Shrimp paste: it has a strong smell but makes the broth authentic; use 1 extra tbsp fish sauce if you cannot find it.
• Traditional extras: pork hock and Vietnamese ham are often added; the shank alone is still excellent.
• Make ahead: the broth keeps 3 days in the refrigerator and tastes better reheated. It freezes for 3 months; cook the noodles fresh.