Bun Rieu Vietnamese Soup: A Tangy Crab and Tomato Bowl

Bun rieu is a Vietnamese noodle soup with a savory pork broth, tomato, rice vermicelli, and soft crab-and-pork rafts, usually served with fresh herbs and lime. Its bright, gently tangy broth balances the rich crab, while diners can season each bowl with shrimp paste and chile to taste; family and regional versions vary.

Ingredients

2 lb pork neck bones (900 g), rinsed
12 cups water (2.8 L)
1 medium yellow onion (about 150 g), peeled and halved
1 tsp fine salt (5 g), plus more to taste
1 oz dried shrimp (28 g), plus ½ cup hot water (120 ml) for soaking
8 oz ground pork (225 g)
8 oz lump crab meat (225 g), picked over for shell
1 can crab paste in soybean oil, about 5 oz (142 g); stir the contents before measuring
2 large eggs (about 100 g without shells)
1 tbsp fish sauce (15 ml), plus more to taste
½ tsp ground black pepper (1 g)
1 tbsp neutral oil (15 ml)
1½ lb ripe tomatoes (680 g), cut into wedges
1 tbsp annatto oil (15 ml), optional, for a deeper orange-red color
1 lb dried rice vermicelli (454 g)
2 cups bean sprouts (about 200 g)
1 cup Vietnamese perilla leaves (about 20 g), torn; substitute Thai basil if needed, though the aroma will differ
1 cup mint leaves (about 20 g), torn
4 scallions (about 60 g), thinly sliced
2 limes (about 120 g), cut into wedges
2 small red chiles (about 10 g), thinly sliced, optional
2 tbsp fermented shrimp paste (30 g), for serving, optional

Instructions

Soak the dried shrimp and prepare the garnishes. Cover the dried shrimp with the hot water and soak for 15 minutes, until softened. While they soak, rinse and drain the herbs and bean sprouts, slice the scallions and chiles, cut the limes, and set out the shrimp paste. Drain the shrimp, reserving the soaking liquid, and chop them finely. This small amount adds a deep seafood savoriness to the crab mixture; if you prefer a milder broth, use half.
Blanch the bones. Put the pork bones in a large pot and cover with water. Bring to a boil and cook for 5 minutes. Drain, rinse the bones and pot to remove the gray foam, then return the bones to the clean pot. Blanching gives the broth a cleaner flavor and appearance; do not skip the rinse or use the blanching water as your soup base.
Make the broth. Add 12 cups fresh water, the onion, and salt to the pot. Bring to a boil, then lower the heat so the liquid simmers gently. Partially cover and simmer for 60 minutes, skimming foam from the surface during the first 15 minutes. A quiet simmer keeps the broth clearer than a hard boil. Lift out the bones and onion, then strain the broth if you want a particularly clear soup. Return the broth to the pot.
Mix the crab rafts. In a bowl, combine the ground pork, lump crab, crab paste, eggs, chopped dried shrimp, 1 tablespoon fish sauce, and black pepper. Fold gently until evenly combined without crushing every piece of crab. The mixture should be moist and spoonable; the crab paste seasons it, so wait until the broth is finished before adding extra salt. Keep the bowl chilled if the broth is not ready yet.
Cook the tomatoes. Heat the neutral oil and annatto oil, if using, in a skillet over medium heat. Add the tomato wedges and cook for about 8 minutes, turning them once or twice, until they soften at the edges but mostly hold their shape. Tip the tomatoes and their juices into the broth. Add the reserved shrimp-soaking liquid if it smells clean and pleasantly savory; leave any grit behind.
Poach the crab mixture. Bring the broth back to a gentle simmer. Use two spoons to lower the crab mixture into the pot in walnut-size portions. Avoid stirring for the first few minutes so the portions can set. Simmer gently for 10–12 minutes, until the rafts are firm and cooked through. Check a large raft with a food thermometer: because it contains ground pork and eggs, the center must reach the USDA FSIS safe minimum of 160°F (71°C). Stir in the remaining fish sauce, taste, and adjust salt only if needed.
Cook the noodles and assemble. Cook the rice vermicelli according to its package directions, usually about 4–5 minutes, until tender but not mushy. Drain and rinse briefly with cool water to stop the cooking, then divide among six deep bowls. Ladle in broth, tomatoes, and several crab rafts. Top with scallions, bean sprouts, perilla, and mint, and serve with lime, chile, and shrimp paste at the table.

Tips

Look for the right crab paste. Asian groceries often carry crab paste in soybean oil near other canned seafood or seasonings; it is not the same as plain crab meat. If it is unavailable, use an extra 4 oz (115 g) crab meat and add 1 teaspoon (5 ml) fish sauce plus a small pinch of paprika. The soup will still be savory, but less concentrated and less orange.
Keep the broth at a simmer. A rolling boil can break up the delicate rafts and make the broth cloudy. Once the mixture goes in, give it a few minutes to firm before moving anything around.
Season in stages. Crab paste, fish sauce, and shrimp paste vary in saltiness. Start with the stated amounts, taste the broth after the rafts cook, and let each person add shrimp paste at the table rather than putting the full amount in the pot.
Use a thermometer, not just appearance. The outside of a raft can look done before the center is cooked. Check the thickest one, and return the pot to a gentle simmer if it has not reached 160°F (71°C).

Serving Suggestions

Serve bun rieu immediately while the broth is hot and the noodles are springy. Set out the herbs, sprouts, lime, sliced chile, and fermented shrimp paste separately so everyone can build a bowl to suit their taste. A squeeze of lime gives the tomato broth extra brightness; a small dab of shrimp paste makes it deeper and more pungent, so add it gradually and stir well.

For a more substantial meal, put extra crab rafts and tomato wedges on a platter for the table, or serve a simple side of sliced cucumber. Keep garnishes dry until serving so they stay crisp. If you are serving the soup over time, keep noodles and broth in separate containers and assemble each bowl just before eating; noodles left sitting in broth continue to absorb liquid.

Variations

Many Vietnamese households make bun rieu with different proportions of crab, pork, tomatoes, and broth. For a more crab-forward version, increase the lump crab to 12 oz (340 g) and reduce the ground pork to 4 oz (115 g); keep the eggs so the mixture still holds together. For a lighter, simpler pot, omit the dried shrimp, though the broth and rafts will lose some of their layered seafood flavor.

You can also use prepared chicken or pork stock instead of making broth from bones. Use 12 cups (2.8 L) unsalted or low-sodium stock, warm it with the onion for 20 minutes, and skip the blanching and long bone simmer; this shortens the cooking time, but the soup will have less pork-bone depth. Fresh or refrigerated rice vermicelli can replace dried noodles; cook it according to its package directions and avoid overcooking. If perilla is hard to find, Thai basil is a useful garnish, but it brings a sweeter, more anise-like aroma.

Storage and Reheating

For food safety, refrigerate the soup within 2 hours of cooking. Store the broth, crab rafts, and tomatoes together in a covered container, and keep cooked noodles and fresh herbs separately so the noodles do not swell and the herbs do not wilt. Refrigerated leftovers keep for 3–4 days. If you have assembled bowls already, they can still be saved, but the noodles will soften as they sit.

Reheat only the portion you plan to eat in a saucepan over medium heat, stirring gently so the rafts stay intact. Heat leftovers to 165°F (74°C), checking the center of a raft with a food thermometer. Add a splash of water or broth if the soup has reduced, and cook a fresh portion of noodles if you want a springier texture. Freeze broth and rafts for up to 2 months for best quality; thaw in the refrigerator overnight, reheat to 165°F (74°C), and add freshly cooked noodles and herbs. Freezing may make the crab rafts a little softer.

Frequently Asked Questions

What does bun rieu taste like? It is savory and seafood-rich, with sweetness from ripe tomatoes and a light tang that you can sharpen with lime. The crab-and-pork rafts are tender rather than chewy, and the fresh herbs add a fragrant contrast. Shrimp paste is potent, so it is usually best added a little at a time.

Can I make the broth ahead? Yes. Make the bone broth up to 2 days ahead, cool it promptly, and refrigerate it in a covered container. Reheat it to a simmer before adding the tomatoes and crab mixture. You can also mix the crab raft ingredients a few hours ahead; cover and refrigerate them, then cook them thoroughly in the hot broth just before serving.

Why did my crab rafts fall apart? The broth may have been boiling too hard, or the portions may have been stirred before they set. Keep the liquid at a gentle simmer, lower spoonfuls in carefully, and leave them undisturbed for the first few minutes. A little loose crab is not a problem; the soup will still taste good, even if the rafts are less distinct.

Can I make bun rieu without pork bones? Yes. Use unsalted chicken or pork stock, or a good-quality seafood stock, in place of the water and bones. Stock that is already salted can make the finished soup too salty once crab paste and fish sauce are added, so taste before seasoning. The result will be quicker and still flavorful, though it will not have the same rounded pork-bone broth.

Is shrimp paste necessary? No. It is a traditional, strongly flavored condiment that diners can stir into their own bowls, but the soup is complete without it. If you are unfamiliar with its flavor, start with a small dab on the side of the bowl rather than mixing a full spoonful into the pot.

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Safety notes: safe minimum internal temperatures from USDA FSIS; raw and undercooked fish guidance from the U.S. FDA. Food safety notes

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