Stir in the lemongrass and lime leaf. Sprinkle in the spices, being careful not to burn them, and immediately add the stock and coconut cream. Season with fish sauce, salt, and pepper. Bring to a boil, then lower the heat and simmer gently for 10–15 minutes until the sauce is slightly thickened, aromatic, and flavorful. Taste and adjust the seasoning as necessary, adding more fish sauce if needed.