Red Vietnamese Soup: Bún Riêu with Tomato Crab Noodles

Bún riêu is a Vietnamese noodle soup with a brick-red tomato broth and a savory crab mixture, served over rice vermicelli with fresh herbs and crunchy vegetables. This practical version uses ground pork, crab, and chicken broth for a full-flavored soup without a long stock-making session; recipes vary by region and household.

Ingredients

12 oz (340 g) dried rice vermicelli noodles
3 qt (2.8 L) water, for boiling the noodles
1 tbsp (15 ml) neutral oil
1 medium yellow onion, finely chopped, about 1 cup (150 g)
3 garlic cloves, minced, about 1 tbsp (9 g)
1 tbsp (16 g) tomato paste
1½ lb (680 g) ripe tomatoes, cut into wedges, about 4 cups (600 g)
8 cups (1.9 L) low-sodium chicken broth
2 tbsp (30 ml) fish sauce, divided
1 tsp (5 g) granulated sugar
8 oz (225 g) ground pork
8 oz (225 g) cooked crab meat, picked over for shell fragments
1 large egg (50 g)
1 tsp (5 ml) Vietnamese fermented shrimp paste, or less to taste
¼ tsp (0.5 g) ground black pepper
½ tsp (3 g) fine salt, plus more to taste
4 scallions, thinly sliced, about ½ cup (50 g)
2 cups (60 g) bean sprouts
1 cup (15 g) torn mint leaves
1 cup (15 g) Thai basil leaves
1 lime, cut into 8 wedges, about 2 tbsp (30 ml) juice
1 small red chile, thinly sliced, about 1 tbsp (10 g), optional

Instructions

Prepare the noodles and vegetables. Bring the 3 quarts (2.8 L) water to a boil in a large pot. Cook the vermicelli according to the package directions, usually about 5 to 7 minutes, until tender but not mushy. Drain, rinse briefly under cool water to remove excess starch, and set aside. Chop the onion, garlic, tomatoes, and garnishes while the water heats and the noodles cook. Keep the herbs and sprouts separate from the hot soup until serving.
Build the tomato base. Heat the oil in a large soup pot over medium heat. Add the onion and cook for about 4 minutes, stirring, until softened but not browned. Add the garlic and tomato paste and stir for 30 seconds. Add the tomato wedges and cook for 3 minutes, turning them gently so they begin to soften and release their juices. The tomato paste deepens the color, while ripe tomatoes give the broth its characteristic tangy, red-orange appearance.
Simmer the broth. Pour in the chicken broth and add the sugar, 1 tablespoon (15 ml) of the fish sauce, and ¼ teaspoon (1.5 g) of the salt. Bring the soup to a gentle boil, then lower the heat and simmer uncovered for 18 minutes. Stir occasionally without crushing all the tomato pieces. Taste the broth; add the remaining fish sauce if you want a saltier, more savory base. Keep the soup at a steady simmer rather than a hard boil, which can break up the tomatoes and make the broth cloudy.
Mix and poach the crab mixture. While the broth simmers, combine the ground pork, crab meat, egg, shrimp paste, black pepper, and remaining ¼ teaspoon (1.5 g) salt in a bowl. Mix just until evenly combined; overmixing can make the cooked mixture dense. Use two spoons to form about 12 loose, walnut-size mounds and lower them carefully into the simmering broth. Cook gently for 10 to 12 minutes, turning the mounds once if needed so they cook evenly. Check the center of a mound with a food thermometer: because this mixture contains ground pork and egg, the USDA FSIS safe minimum is 160°F (71°C). If it has not reached that temperature, simmer for a few more minutes and check again.
Finish and serve. Taste the broth once more and adjust with a little salt or fish sauce if needed. Divide the drained noodles among four deep bowls. Ladle in the tomatoes, crab-pork mounds, and hot broth. Top each serving with scallions, bean sprouts, mint, and Thai basil. Offer lime wedges and sliced chile at the table so everyone can adjust the brightness and heat to taste.

Tips

Choose ripe tomatoes. Soft, fragrant tomatoes give the broth more flavor and color than firm, underripe ones. If your tomatoes are pale or out of season, use the measured tomato paste as written and add another teaspoon (5 g) for a deeper red color; avoid adding lots of paste, which can make the soup taste more like pasta sauce.
Use shrimp paste sparingly. Vietnamese fermented shrimp paste, often labeled mắm tôm, is salty and pungent, so a teaspoon is enough to season the crab mixture. It can be difficult to find. If you cannot get it, omit it and add an extra teaspoon (5 ml) of fish sauce; the soup will still be savory but will lack the distinctive fermented aroma.
Handle crab gently. Check cooked crab meat carefully for shell, and fold it into the pork mixture instead of mashing it. Pasteurized canned or refrigerated crab is convenient. Imitation crab is a possible budget substitute, but it is sweeter and less delicate, so reduce the sugar slightly if its flavor is noticeable.
Keep noodles and broth apart. Vermicelli continues absorbing liquid as it sits. Drain it well and portion it into bowls rather than storing it in the soup. Rinsing after boiling helps prevent clumping; do not leave the noodles soaking in water, or they can become waterlogged.

Serving Suggestions

Serve bún riêu hot as a complete meal, with a generous amount of broth and enough noodles in each bowl to catch the crab and tomato. Put extra bean sprouts, herbs, lime, and chile on the table rather than cooking them into the pot. Diners can add the sprouts for crunch, squeeze in lime to sharpen the tomato broth, and use chile for heat. A small dish of fish sauce is useful for anyone who wants a saltier bowl, though the soup should already taste balanced before it reaches the table.

For a casual meal with several people, set out the toppings in separate bowls and let everyone build their own serving. The soup is filling on its own, but a light side of sliced cucumber or a simple plate of blanched greens also works well. If serving rice vermicelli to guests unfamiliar with it, provide chopsticks and a soup spoon; the spoon makes it easier to enjoy the broth and small pieces of crab together.

Variations

More traditional crab flavor: Some Vietnamese versions use canned Vietnamese crab paste or a prepared crab mixture, and recipes vary in their use of shrimp paste and other seafood. If you find a jar of Vietnamese crab paste, check its salt level and follow its label for handling. You can replace up to half of the cooked crab with the paste, but reduce the added fish sauce and salt because the paste is usually seasoned. The result will have a more concentrated, fermented seafood flavor than this mild, accessible version.

Make it without pork: Replace the ground pork with an equal amount of finely chopped, firm tofu, or use another 8 oz (225 g) cooked crab. Tofu will not bind into the same tender mounds, so leave it in small cubes and add it directly to the broth for the last 5 minutes. For a vegetarian bowl, use vegetable broth and omit fish sauce, shrimp paste, crab, and pork; season with a vegetarian fish-sauce alternative. This changes the dish substantially, but the tomato broth, noodles, and fresh toppings still make a satisfying soup.

Adjust the heat and richness: Keep the pot mild and serve fresh chile separately, or add ½ teaspoon (2 g) chile flakes with the garlic for gentle heat throughout. For a richer broth, replace 1 cup (240 ml) of the chicken broth with water and simmer the soup with a small piece of dried shrimp, then remove it before serving. Dried shrimp is optional and can be quite salty, so taste before adding more seasoning.

Storage and Reheating

Refrigerate leftover broth and crab-pork mounds within 2 hours of cooking, in a covered container. They keep for 3 to 4 days in the refrigerator. Store the noodles, herbs, sprouts, and lime separately; fresh herbs and sprouts are best used within a day or two, and cooked noodles can soften quickly. For longer storage, freeze the broth and cooked mounds in a freezer-safe container for up to 2 months for best quality. Thaw overnight in the refrigerator. Freeze noodles only if necessary, since their texture may become softer after thawing.

Reheat only the amount you plan to eat. Warm the broth and mounds in a saucepan over medium heat, stirring gently, until steaming throughout; check that leftovers reach 165°F (74°C). Add a splash of water or broth if the soup has reduced. Reheat noodles separately by briefly dipping them in hot water, then drain and place them in bowls before ladling the hot soup over them. Avoid boiling the crab mixture hard, which can make the pork firm and break apart the crab.

Frequently Asked Questions

What makes Vietnamese soup red? In this bún riêu-style recipe, ripe tomatoes and a small amount of tomato paste color the broth. The finished soup is usually red-orange rather than bright red. Some cooks use annatto oil or other ingredients for a deeper color, and the shade varies with the tomatoes and the particular family or regional recipe.

Is bún riêu spicy? The broth in this recipe is not inherently hot. Its main flavors are tangy tomato, savory crab, and fermented shrimp paste. Chile is served separately, so you can leave it out for a mild bowl or add fresh slices to make an individual serving spicy.

Can I make the soup ahead? Yes. Make the broth and crab-pork mounds up to 3 days ahead and refrigerate them promptly. Cook or reheat the noodles close to serving time, and keep herbs and sprouts separate. Reheat the soup to 165°F (74°C), then assemble bowls just before eating so the noodles and toppings keep their best texture.

Can I use frozen crab meat? Yes. Thaw it safely in the refrigerator, drain away excess liquid, and pick through it for shell fragments before mixing. Wet crab can loosen the pork mixture, so pat it dry gently with paper towels. The crab should be cooked before it is added to this recipe; the pork-and-crab mounds still need to reach 160°F (71°C) because they contain ground pork and egg.

What can I use instead of rice vermicelli? Thin rice sticks or another plain rice noodle are suitable substitutes. Follow the package instructions because soaking and boiling times differ by noodle thickness. In a pinch, use another mild noodle, but wheat noodles change the bowl’s texture and are not the usual choice for bún riêu. Keep any substitute separate from the broth until serving.

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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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