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Authentic Thai Vegan Hot and Sour Soup

Kathleen R. Coffey
A comforting and tangy vegan soup combining pineapple, tamarind, lemongrass, mushrooms, and tofu, served with rice noodles and fresh greens.
Perfect for quick weeknight dinners or meal-prep-friendly lunches.
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Prep Time 15 minutes
Cook Time 30 minutes
Total Time 45 minutes
Course Main Course, Soup
Cuisine Asian, Vegan
Servings 4

Equipment

  • 1 large stockpot (6–8 qt)
  • 1 Fine mesh sieve
  • 1 Chef’s Knife
  • 1 Wooden spoon
  • 1 Slotted Spoon

Ingredients
  

Tamarind Juice

  • 80 g tamarind pulp ⅓ cup
  • 240 ml boiling water 1 cup

Broth

  • 30 ml oil 2 tbsp
  • 2 tbsp finely chopped lemongrass
  • 1 medium tomato sliced
  • 170 g pineapple peeled and cut into chunks (≈1 cup)
  • 4 –5 cremini mushrooms quartered
  • 1.5 liters water 6 cups
  • 2 lemongrass stalks slightly crushed
  • 50 g granulated sugar ¼ cup
  • 3 tsp salt
  • 1 tsp mushroom seasoning optional but recommended
  • 6 pieces fried tofu
  • ¼ Thai chili finely sliced

Add-ins

  • Cooked white rice noodles
  • Handful of Thai basil
  • Vegan bologna or vegan sausages optional

Instructions
 

  • Prepare Tamarind Juice:
    Tamarind Soaking: Place the tamarind pulp in a medium-sized bowl and pour over 1 cup (240 ml) of freshly boiling water.
    Allow the pulp to sit for about 10 minutes so it softens and releases its natural tangy flavor.
    Stir and Break Apart: Using a wooden spoon or spatula, gently press and stir the tamarind to help dissolve it into the water.
    You want a smooth, rich, tangy liquid without large clumps.
    Strain the Pulp: Place a fine-mesh sieve over another bowl and pour the tamarind mixture through it.
    Press down lightly with the back of a spoon to extract as much juice as possible. Discard the remaining pulp.
    Set the tamarind juice aside; this will be the heart of the soup’s signature sour flavor.
  • Sauté Aromatics and Fruits:
    Heat the Oil: In a large stockpot (6–8 quarts), warm 2 tablespoons of neutral oil over medium heat.
    The oil should shimmer lightly, indicating it’s ready for sautéing.
    Add Lemongrass: Add the finely chopped lemongrass and sauté for about 1–2 minutes until fragrant.
    The aroma should be bright and citrusy, a clear sign that the flavor base is developing.
    Incorporate Tomato and Pineapple: Add the sliced tomato and pineapple chunks to the pot.
    Sauté together for 5 minutes, stirring occasionally, until the tomato softens and begins to release its juices, and the pineapple edges turn lightly golden.
    This step brings out the natural sweetness that balances the soup’s sour and spicy notes.
  • Add Mushrooms:
    Quarter and Sauté: Add the quartered cremini mushrooms to the pot. Stir them gently to coat them in the aromatic mixture.
    Continue sautéing for 2–3 minutes until the mushrooms soften slightly but still maintain their texture. Mushrooms add a savory, umami depth that enriches the broth.
  • Build the Broth:
    Add Water: Pour 6 cups (1.5 liters) of water into the pot. Stir to combine the sautéed aromatics, fruit, and mushrooms with the liquid.
    Add Whole Lemongrass Stalks: Lightly crush the remaining 2 lemongrass stalks with the back of a knife and drop them into the pot. Crushing releases additional essential oils, intensifying the soup’s flavor.
    Season the Broth: Stir in ¼ cup (50 g) granulated sugar, 3 teaspoons salt, and 1 teaspoon mushroom seasoning (optional but recommended). Taste as you go to ensure a perfect balance between sweet, sour, and savory.
    Incorporate Tamarind Juice: Pour the prepared tamarind juice into the broth and stir well. This addition will bring a signature tang that is essential to authentic Bún Thái.
  • Add Tofu and Optional Ingredients
    Include Fried Tofu: Carefully add 6 pieces of fried tofu to the simmering broth. Tofu will absorb the flavors of the soup while adding protein and texture.
    Optional Add-Ins: If desired, add vegan bologna or vegan sausages, as well as fresh greens such as morning glory, green beans, or spinach. These ingredients contribute extra color, nutrients, and variety.
  • Simmer the Soup:
    Bring to a Boil: Increase the heat slightly to bring the soup to a gentle boil.
    Simmer Uncovered: Reduce the heat to maintain a low simmer and cook uncovered for 25–30 minutes.
    Stir occasionally to prevent sticking and to help flavors meld. This slow simmer allows the pineapple, lemongrass, and tamarind to infuse the broth fully.
    Taste and Adjust: Before serving, taste the broth and adjust seasoning as needed. You can add more salt, sugar, or sliced Thai chili for extra heat.
  • Cook Rice Noodles:
    Boil Noodles: In a separate pot, bring water to a boil and cook rice noodles according to package instructions.
    Traditional round rice noodles are recommended, but flat or thin noodles will also work.
    Drain and Rinse: Once cooked, drain the noodles and rinse briefly under cool water to prevent sticking. Divide the noodles evenly into serving bowls.
  • Assemble the Soup:
    Distribute Add-Ins: Using a slotted spoon, carefully add tofu, mushrooms, pineapple, and any greens into each bowl on top of the noodles.
    Pour Broth Over: Ladle the piping hot broth over the noodles and add-ins, ensuring each bowl receives a balanced mixture of all ingredients.
    Garnish and Serve: Finish with a handful of fresh Thai basil leaves and optional sliced chili on top.
    Serve immediately while hot, allowing each bite to feature a perfect balance of sweet, sour, spicy, and savory flavors.

Notes

  • Use fresh tamarind pulp for the best tangy flavor; bottled juice can be more acidic or concentrated.
  • Slightly crush the lemongrass stalks to release essential oils and deepen the aroma.
  • Fry the tofu in advance to add texture and prevent it from becoming soggy in the broth.
  • Adjust the Thai chili slices to control the soup’s spiciness to your preference.
  • This soup is versatile—feel free to add greens such as morning glory, spinach, or green beans for extra nutrition and color.
  • Round rice noodles are traditional, but flat or vermicelli noodles also work well.