Begin by prepping your ingredients for the Chicken Tom Yum Soup. Smash 3-4 stalks of fresh lemongrass, slice 8 pieces of galangal without peeling, and tear 6 kaffir lime leaves to release their aromatic oils. Lightly smash 2-5 fresh Thai chilies based on your preferred spice level, and slice 1 small white onion thinly to add sweetness to the broth.

In a large pot, pour in 4 cups of chicken broth and bring it to a rolling boil over medium-high heat. Add the smashed lemongrass, galangal slices, torn kaffir lime leaves, and smashed chilies. Allow this aromatic concoction to boil for 15 minutes.

Lower the heat to medium and incorporate 1 lb of thinly sliced chicken thighs or breasts, along with the sliced white onion and 2 cups of your favorite mushrooms. Simmer for an additional 15 minutes.

Once the chicken is cooked through, stir in 2-3 small tomatoes cut into wedges. Turn off the heat, allowing the residual warmth to gently cook the tomatoes.

Incorporate 3-4 tablespoons of Thai roasted chili paste (if using), 1-2 tablespoons of tamarind paste, juice from 2-3 limes, and 2-3 tablespoons of fish sauce into the pot. Sprinkle in 1 tablespoon of brown sugar, stirring until all ingredients are well-combined.

Ladle the fragrant Chicken Tom Yum Soup into warm bowls and garnish generously with freshly chopped cilantro.