Combine chicken thighs, thinly sliced ginger, and four whole green onions in a large pot.
2
Cover with water by 1-inch and simmer until the chicken is cooked, about 30 to 40 minutes. Remove the chicken and set aside until cool enough to shred. Strain broth, and discard ginger and green onions.
3
Add cauliflower and simmer until it breaks apart and becomes mushy.
4
Add shredded chicken, finely minced ginger, and fish sauce.
5
Portion chicken mixture into bowls and garnish with cilantro and thinly sliced green onions. Serve with a small lime wedge and chili oil.