For the paste:
1/4 teaspoon white peppercorns
2 lemongrass stalks, outer leaves stripped away (tender hearts only)
3 makrut lime leaves, backbone removed and shredded finely
1 tablespoon finely chopped galangal
1/2 cup cilantro stalks, chopped
1 large shallot, chopped (about 3 tablespoons)
4 garlic cloves, crushed
For the soup:
1 cup coconut milk, stirred
1 cup vegetable or chicken stock
8 ounces white shimeji mushrooms, roots removed and kept whole (or white button mushrooms, thickly sliced)
12 to 16 medium-sized shrimp, peeled and deveined (with the tail left on, if you prefer)
Sugar and salt, to taste
Small handful Thai basil leaves, torn (optional)
For the chili sauce:
2 tablespoons fish sauce
1 tablespoon lime juice
3 red or green hot bird's eye chilies, finely sliced
First, make the paste. Dry-roast the peppercorns in a skillet over high heat until fragrant, 1 to 2 minutes. Transfer to a bowl and let cool. Place the cooled peppercorns and the remaining paste ingredients, one by one, into a mortar and pestle and pound into a fine paste (see Recipe Notes). You can also place all the ingredients in a powerful blender and blend to a fine paste. Add the extra 4 tablespoons of coconut milk to loosen the paste and make it easier to blend.
→ Make-Ahead: This paste can be made up to a week in advance and kept refrigerated, or you can freeze it for up to 3 months. If making ahead, do not add coconut milk.
To make the soup, place the paste in a saucepan, and add the coconut milk and stock. Bring it up to a gentle simmer (do not boil). Simmer gently for about 5 minutes, then add the mushrooms. Cook for a couple of minutes until the mushrooms are tender, then add the shrimp. When the shrimp turn pink (2 to 3 minutes, depending on their size), turn off the heat and season the soup to taste with the salt and sugar, adding more coconut milk if desired. Add the Thai basil leaves, if using.
Meanwhile, combine the ingredients for the chili sauce, and set aside.
To serve, ladle the soup into bowls and serve with the chili sauce. Each person can season the soup to their taste with the sauce (I use about 1 teaspoon of sauce). The sauce should taste perfectly balanced between hot, salty, sweet and slightly tangy.
Recipe Notes
- You can replace the shrimp and mushrooms with shredded cooked chicken, sliced Thai eggplants, vegetables, or any kind of seafood. I sometimes use baby scallops, mussels, clams, and white fish fillets to make a hearty seafood version of this soup.
- You can make the paste ahead and store it in the fridge. If making it ahead, do not add any coconut