Vietnamese sour soup, also known as "canh chua," is a flavorful and tangy soup made with a variety of vegetables and typically includes fish or shrimp. Here's a simple recipe to cook Vietnamese sour soup:

Ingredients:

- 500g fish or shrimp (can be catfish, tilapia, or other firm-fleshed fish)

- 2 tablespoons vegetable oil

- 3 cloves garlic, minced

- 1 small onion, sliced

- 2 tomatoes, cut into wedges

- 1 cup pineapple chunks

- 1 cup okra, sliced

- 4 cups water or fish stock

- 3 tablespoons tamarind pulp or tamarind concentrate

- 2 tablespoons fish sauce

- 1 tablespoon sugar

- 1 teaspoon chili flakes (optional)

- Handful of fresh herbs such as Vietnamese coriander (rau răm) or Thai basil

- Lime wedges for serving

Instructions:

1. If using fish, clean and cut it into chunks. If using shrimp, peel and devein them.

2. In a large pot, heat the vegetable oil over medium heat. Add the minced garlic and sliced onion, and sauté until fragrant.

3. Add the fish or shrimp to the pot and cook for a few minutes until they are partially cooked.

4. Add the tomatoes, pineapple chunks, and okra to the pot. Stir them together and cook for another few minutes.

5. Pour in the water or fish stock and bring it to a boil. Reduce the heat to low and let it simmer for about 10 minutes.

6. Add the tamarind pulp or tamarind concentrate to the pot and stir well to dissolve it. This will give the soup its tangy flavor.

7. Stir in the fish sauce, sugar, and chili flakes (if using). Taste the soup and adjust the seasoning according to your preference.

8. Simmer the soup for an additional 5-10 minutes, or until the fish or shrimp is fully cooked and the vegetables are tender.

9. Remove the soup from heat and garnish with fresh herbs such as Vietnamese coriander or Thai basil.

10. Serve hot with steamed rice and lime wedges on the side for squeezing into the soup for extra tanginess.

Enjoy your delicious Vietnamese sour soup!