Heat olive oil in a soup pot over medium heat.

Sauté onion, garlic, and salt until onions are translucent.

Add ginger, red pepper, coriander, and cumin; cook until fragrant (about 2 minutes).

Prepare lemongrass by bisecting it lengthwise and removing the core.

Chop the tender part of the lemongrass stalk and add it to the spices.

Tenderize chicken breast with a meat pounder and cut it into thin strips.

Add chicken to the onion and spices and cook until chicken is white on the outside.

Stir in water, coconut milk, fish sauce, and unchopped lemongrass stalk.

Simmer until chicken is cooked and flavors are well blended (15 to 20 minutes).

Add bok choy and cilantro and simmer for another 5 minutes.

Remove lemongrass stalk before serving.