Gather all ingredients and equipment.
Make the Nuoc Cham:
Place the garlic, sugar, rice vinegar, lime juice, sambal, water, and fish sauce in a small bowl.
Whisk until smooth. Set aside.
Make the Broth:
Heat sesame oil in a medium pot over medium high heat. Add ginger, garlic, lemongrass and scallions and saute for 2 minutes until fragrant, taking care not to burn them.
Add stock, soy sauce and cilantro and bring to a boil. Reduce heat to continue simmering for 10 minutes. While the broth is simmering, prepare the chicken and vegetables.
For the Dish:
When the broth is flavorful, bring to poaching temperature (160-180°F / 71-82°C), add the chicken breast, and cook it until the internal temperature is 165°F.
Adjust heat as necessary to keep liquid between 160-180°F. Do not boil!
If necessary, add water or stock to the pot so that the chicken is completely submerged when cooking.
Once chicken is cooked, remove it from the pot, and set aside to cool before slicing.
Strain the broth and reserve the liquid. Pour the strained liquid back in to the pot and bring to a boil.
When the liquid is boiling, add the broccoli, carrots, and bok choy, and cook for 4-5 minutes until al dente. Remove from heat.
Add noodles to the hot liquid and let stand for 5 minutes or according to package cooking instructions.
When the noodles have cooked, add nuoc cham, bok choy, and chicken and gently stir to incorporate.
Serve immediately. Garnish with lime wedges, cilantro, and sesame seeds.