To begin, place the chicken in your Dutch oven with enough water to cover by an inch, about 6 cups. Bring the water to a boil, reduce the heat, and simmer until the chicken is tender, about 20 minutes.
Transfer the chicken to a cutting board.
Reserve 2 cups of the chicken water and discard the rest.
Add the chicken stock, onion, ginger, carrots, celery, garlic, and turmeric, then stir.
Bring it to a boil, then reduce heat to medium, cover, and cook for about 10 minutes.
Meanwhile shred the chicken.
While the vegetables are cooking, separate the cauliflower florets from the thick stem and place the florets in your food processor. Pulse them several times until it resembles grains of rice.
Add the chicken and riced cauliflower to the soup, along with the remaining ingredients.
Cook until the vegetables are just tender.
Add additional salt and pepper to taste, if needed.
Notes
If you do not have a food processor, you can cut the cauliflower up into small pieces.