Ready in 45 minutes
It?s hard to understand why a soup that looks so simple needs to include so many ingredients. Why not just stir in a dollop of store-bought Thai curry paste instead and call it a day? One spoonful will reveal the answer: This soup has many layers in its complexity, but the overall effect is of cleanness and freshness?in short, well worth a trip to an Asian market. Adding a generous amount of chicken and serving the soup over jasmine rice might not be strictly traditional, but it transforms it into a satisfying meal.
Cut off and discard top of lemongrass, leaving 6-inch stalks, then finely chop. Cook lemongrass, shallots, and garlic in oil in a large heavy pot over medium-low heat, stirring occasionally, until well browned, 12 to 15 minutes.
Add stock, reserved tomato juice, tamarind, fish sauce, chiles, lime leaves, and ginger and simmer, uncovered, 30 minutes.
While soup simmers, freeze chicken breast just until slightly firm, 20 to 30 minutes, then thinly slice crosswise.
Strain stock through a fine-mesh sieve into a large saucepan, pressing hard on and then discarding solids. Return to a simmer and stir in chicken, diced tomatoes, snow peas, and basil. Gently simmer just until chicken is cooked through, 1 to 2 minutes. Season with additional fish sauce and salt.