Step 1

In a large pot, whisk the chicken broth with the coconut milk and turmeric until combined. Add the fish sauce, ginger and garlic. Squeeze the juice from the lime into the pot and then add the citrus halves. Bring to a simmer over moderate heat.

Step 2

Add the chicken breasts, cover and reduce the heat to low. Gently simmer, flipping once, until cooked through, 15 to 20 minutes. Using tongs, transfer the chicken breasts to a plate and let cool slightly. Shred the meat using two forks. Discard the lime halves.

Step 3

Add the bok choy, bell pepper, carrot and white and light green scallion parts to the soup and bring to a simmer. Cook until the vegetables are just tender, about 5 minutes. Add the shredded chicken to the soup and season with more fish sauce, if needed.

Step 4

Ladle the soup into shallow bowls and garnish with the julienned scallion greens, cilantro sprigs and thinly sliced Fresno pepper, if using. Serve right away, passing with lime wedges at the table.