How to Make Vegetarian Fermented Fish Noodle Soup at Home

This vegetarian fermented fish noodle soup features a savory-sweet lemongrass broth, mushrooms, tofu, eggplant, plant-based roast pork, and fresh vegetables. Although it contains no fish-based fermented sauce, it retains the dish’s distinctive character through fermented soybean paste, vegetable broth, and balanced seasoning. Follow this recipe to prepare a satisfying meal for the whole family.

Recipe information

• Servings: 4
• Preparation time: About 25 minutes
• Cooking time: About 45 minutes
• Total time: About 1 hour 10 minutes
• Difficulty: Intermediate

What makes vegetarian fermented fish noodle soup special?

This style of fermented noodle soup is familiar in Vietnam’s Mekong Delta and is known for its deeply flavored broth and distinctive aroma. In this vegetarian version, fish-based fermented sauce is replaced with a plant-based alternative, such as fermented soybean paste.

The broth is simmered with daikon, sweet corn, onion, and lemongrass for natural sweetness. Vegan fermented paste contributes saltiness and depth, while mushrooms, tofu, eggplant, and fresh vegetables provide a variety of flavors and textures. Plant-based roast pork is heated separately and added just before serving for a crisp finish and a presentation reminiscent of traditional Mekong Delta-style fermented noodle soup.

Because the salt level varies among vegan fermented products, the most important rule is to add the paste gradually and taste the broth after each addition. This keeps the soup rich without making it excessively salty.

Vegetarian fermented fish noodle soup ingredients

The quantities below make four servings.

Vegan fermented paste

• 80–100 g fermented soybean paste or vegan fermented paste
• 300 ml warm water for dissolving and straining the paste

If you are using a product for the first time, begin with 80 g. Add the remainder only after tasting the broth.

Vegetable broth

• 1.5 liters water
• 1 daikon radish, about 300 g
• 1 ear of sweet corn, about 250 g
• 1/2 pineapple, about 200 g
• 3 lemongrass stalks
• 1 onion, about 150 g

Bruise two lemongrass stalks for the broth and finely mince the remaining stalk for sautéing.

Toppings

• 200 g ready-made plant-based roast pork
• 200 g oyster mushrooms
• 150 g straw mushrooms or king oyster mushrooms
• 300 g firm white tofu
• 1 eggplant, about 250 g

Plant-based roast pork is an optional topping. Check the product label to make sure it is suitable for your vegetarian or vegan diet. You may use just one type of mushroom, but avoid adding too many strongly flavored varieties because they can overpower the fermented paste and lemongrass.

Noodles and fresh vegetables

• 600 g fresh rice vermicelli
• 200 g shredded water spinach
• 150 g shredded banana blossom
• 150 g bean sprouts
• 50 g chives and mixed fresh herbs
• 1–2 limes
• 1–2 fresh chilies

Seasonings

• 20 g rock sugar, about 1 1/2 tablespoons
• 1 tablespoon soy sauce
• 1 teaspoon vegan seasoning powder, optional
• 1/2 teaspoon salt, only if needed
• 1 tablespoon cooking oil
• 1 teaspoon annatto oil
• 1 minced lemongrass stalk, taken from the prepared lemongrass
• 1 minced chili, reduced or omitted if preferred

These seasoning quantities are a starting point. Taste and adjust them according to the salt level of your fermented paste.

How to choose vegan fermented paste

The fermented paste determines much of the dish’s flavor. Keep the following points in mind when choosing a product:

• Read the ingredient list: Make sure the product contains no fish, shrimp, or animal-derived flavor enhancers, especially when cooking for vegans.
• Check the product’s condition: Do not use paste with unusual odors, mold, or signs of spoilage beyond its normal fermented characteristics.
• Inspect the packaging: Avoid products in swollen, leaking, or damaged containers.
• Choose a traceable product: Look for clear labeling, a production date, an expiration date, and complete storage instructions.

When trying a fermented paste for the first time, dissolve a small amount in warm water and check its aroma and saltiness before adding it to the pot. If you cannot find a product intended for this type of noodle soup, use fermented soybean paste and balance it with lemongrass, pineapple, mushrooms, and vegetable broth.

How to make vegetarian fermented fish noodle soup

Step 1: Prepare the ingredients

Peel and rinse the daikon, then cut it into 3–4 cm pieces. Husk and rinse the corn, then cut it into three or four sections. Peel and halve the onion. Remove the pineapple eyes and cut the flesh into bite-sized pieces.

Rinse all three lemongrass stalks. Bruise and cut two stalks into sections for the broth, then finely mince the remaining stalk for sautéing.

Trim the mushroom stems, rinse the mushrooms quickly under running water, and drain well. Tear the oyster mushrooms into bite-sized pieces and halve any large straw mushrooms. Do not soak mushrooms for too long because they absorb water easily and may lose their pleasantly chewy texture.

Rinse the eggplant and cut it into bite-sized pieces. Soak it in lightly salted water for about 10 minutes, then rinse again and drain thoroughly.

Cut the tofu into bite-sized cubes. Pan-fry the pieces in a small amount of oil until golden on all sides, then set them aside.

Cut the plant-based roast pork into slices about 1–1.5 cm thick. Pan-fry over medium heat for 3–4 minutes, or heat it in an air fryer at 180°C for 6–8 minutes, until the outside is golden and slightly crisp. Set it aside and do not add it to the broth.

Pick through the fresh vegetables, wash them thoroughly, and drain well. To help shredded water spinach and banana blossom retain their color, soak them briefly in clean water with a little lime juice, then rinse before serving.

Step 2: Prepare the vegetable broth

Bring 1.5 liters of water to a boil in a large pot. Add the corn, daikon, onion, and two bruised lemongrass stalks. When the water returns to a boil, reduce the heat and simmer for about 30 minutes. Skim off any foam gently to keep the broth clear.

After 30 minutes, remove the onion and lemongrass. Keep the corn and daikon in the pot for serving, or remove them if preferred.

Step 3: Dissolve and strain the vegan fermented paste

Place 80 g of vegan fermented paste in a bowl. Add 300 ml warm water and stir until combined. Strain the mixture through a fine sieve, keeping the liquid and discarding any large solids.

Do not pour all the strained liquid into the broth at once. Divide it into two or three portions and add it gradually when finishing the soup. If the broth is still too mild after seasoning, dissolve and add some of the remaining paste.

Step 4: Sauté the mushrooms and eggplant

Heat 1 tablespoon cooking oil and 1 teaspoon annatto oil in a pan. Add the minced lemongrass and chili, then sauté over medium heat until fragrant.

Add the mushrooms and stir-fry for about 2 minutes, then transfer them to a plate. Add the eggplant to the same pan and cook for about 2 minutes, until the surface begins to firm up. Turn off the heat. The mushrooms and eggplant do not need to cook completely because they will finish cooking in the broth.

Step 5: Finish the broth

Pour the strained fermented-paste liquid into the vegetable broth one portion at a time. Stir and taste after each addition to control the salt level.

Add 20 g rock sugar, 1 tablespoon soy sauce, and 1 teaspoon vegan seasoning powder if using. Add salt only after tasting and only if the broth still needs it.

Add the eggplant first and cook for about 4 minutes. Add the sautéed mushrooms, fried tofu, and pineapple, then cook over medium heat for another 2–3 minutes before turning off the heat. Adding the ingredients in this order allows the eggplant to become tender without falling apart while preserving the mushrooms’ texture.

The finished broth should have a balanced savory-sweet flavor, a clean aftertaste, a noticeable lemongrass aroma, and no harsh fermented smell.

Step 6: Assemble and serve

Briefly blanch the fresh rice vermicelli in boiling water and divide it among four bowls. Arrange the mushrooms, tofu, and eggplant on top, then ladle in the hot broth. Add the plant-based roast pork last to keep its exterior crisp and avoid soaking it in the broth for too long.

Serve the vegetarian fermented fish noodle soup hot with shredded water spinach, banana blossom, bean sprouts, chives, and fresh herbs. Add lime, fresh chili, or a small amount of vegan satay chili sauce to taste.

Tips for flavorful vegetarian fermented fish noodle soup that is not overly salty

• Add the fermented paste gradually: Salt levels vary by product. Add a small amount, stir, and taste before adding more.
• Use sugar sparingly: Most of the sweetness should come from the corn, daikon, and onion. Rock sugar should only balance the aftertaste.
• Do not add too much pineapple: About 200 g is enough for four servings. Too much can make the broth overly tart or sweet.
• Strain the fermented paste: Straining removes large solids and gives the broth a smoother texture.
• Do not overcook the mushrooms: Stir-fry them briefly and simmer them in the broth for only another 2–3 minutes to retain their texture.
• Add the eggplant before the mushrooms: Eggplant takes longer to cook but can fall apart if simmered excessively.
• Heat the plant-based roast pork separately: Do not add it directly to the pot because it will absorb the broth and quickly lose its crispness.
• Check packaged vegan ingredients: When cooking for vegans, read the labels on the fermented paste, soy sauce, seasoning powder, satay sauce, tofu, and plant-based roast pork.

If the broth becomes too salty, add a small amount of unseasoned vegetable broth at a time. Avoid trying to correct it with a large amount of pineapple or sugar because this can make the flavor unbalanced.

How to store vegetarian fermented fish noodle soup

If you have leftovers, store the broth, noodles, and raw vegetables separately:

• Do not leave cooked broth at room temperature for more than 2 hours.
• Transfer the broth to clean, covered containers and refrigerate it for up to 3–4 days.
• Reheat the broth thoroughly and warm only the amount you intend to serve. Avoid reheating the same batch repeatedly.
• Fresh rice vermicelli and raw vegetables are best consumed on the same day. Do not store them submerged in the broth.
• Discard the broth if its smell, color, or texture appears unusual.

Suggested menu to serve with vegetarian fermented fish noodle soup

Vegetarian fermented fish noodle soup contains carbohydrates, tofu, mushrooms, plant-based roast pork, and vegetables, making it a satisfying main course. For a family meal, consider the following menu:

• Appetizer: Vegan lotus stem salad or mixed vegetable salad
• Main course: vegetarian fermented fish noodle soup with mushrooms, tofu, eggplant, and plant-based roast pork
• Fresh accompaniments: Shredded water spinach, banana blossom, bean sprouts, and herbs
• Dessert: Seasonal fresh fruit
• Drink: Herbal tea or a lightly sweetened refreshing beverage

Herbal tea makes a refreshing accompaniment to this noodle soup

For more family meal ideas, explore our guide to the top 10 Vietnamese vegetarian noodle dishes.

Frequently asked questions about vegetarian fermented fish noodle soup

What can I use if I cannot find vegan fermented paste?

Use fermented soybean paste or another suitable bean-based fermented sauce. The final flavor will vary by product, so add it gradually and balance it with lemongrass, pineapple, mushrooms, and vegetable broth.

Is vegetarian fermented fish noodle soup suitable for a fully vegan diet?

It can be fully vegan if every ingredient is plant-based. Check the labels on the fermented paste, soy sauce, seasoning powder, satay sauce, plant-based roast pork, and other packaged products.

Is plant-based roast pork required?

No. It is an optional topping that makes the bowl more substantial and resembles the presentation of Mekong Delta-style fermented noodle soup served with roast pork. If you prefer not to use mock meat, add more tofu or mushrooms without changing the broth.

Which mushrooms work best in vegetarian fermented fish noodle soup?

Oyster mushrooms, straw mushrooms, and king oyster mushrooms are all suitable because of their natural sweetness and pleasantly chewy texture. You may combine two varieties, but avoid using too many strongly flavored mushrooms.

Can I prepare the broth one day in advance?

Yes. Cool the cooked broth promptly, transfer it to a covered container, and refrigerate it. Reheat it thoroughly before adding separately prepared noodles and vegetables.

How can I fix broth that is too salty?

Add a small amount of unseasoned vegetable broth, stir, and taste again. Do not add excessive sugar, as the broth may become harshly sweet while remaining unbalanced.

Can people managing their weight eat vegetarian fermented fish noodle soup?

Yes, provided the portion suits their individual dietary needs. Reduce the amount of noodles, add more vegetables and mushrooms, pan-fry the tofu instead of deep-frying it, and limit sugar and highly processed plant-based products. The actual energy value depends on the precise quantities and products used, so a single calorie estimate does not apply to every bowl.

Conclusion

To make delicious vegetarian fermented fish noodle soup, control the saltiness of the fermented paste, develop natural sweetness from vegetables, and add the mushrooms and eggplant at the right time. Heat the plant-based roast pork separately and place it on the bowl just before serving to preserve its crisp texture. When the savory, sweet, and lemongrass notes are balanced, the soup tastes rich without becoming heavy.

If you do not have time to prepare the dish yourself, reserve a table at Vô Úy Vegetarian Restaurant for a convenient and thoughtfully prepared vegetarian dining experience.