Prepare the Broth:
Bring water or chicken stock to a boil in a large pot.
If using whole prawns, add the shells and heads to the pot for extra flavor. Simmer for 10 minutes, then strain and return the broth to the pot.
Infuse with Aromatics:
Add lemongrass, kaffir lime leaves, galangal, garlic, and chilies to the broth.
Simmer for another 10 minutes to extract maximum flavor.
Cook the Vegetables & Protein:
Add mushrooms, tomatoes, and peeled shrimp to the broth.
Cook until the shrimp turn pink and are fully cooked (about 3-4 minutes).
Season the Soup:
Stir in fish sauce, lime juice, and sugar.
Taste and adjust the seasoning as needed for a perfect balance of salty, sour, spicy, and sweet.
Make It Creamy (Optional):
For a creamy version, stir in Thai chili paste and evaporated milk (or coconut milk).
Serve & Garnish:
Ladle the soup into bowls and garnish with fresh cilantro.
Serve with extra lime wedges for an extra tangy kick.