Fill a large pot with water and add spring onions, lemongrass, lime leaves, ginger slices, salt, galangal paste, dashi powder, turmeric powder, and Shaoxing wine.Stir to combine and bring to a boil over medium-high heat.
Once boiling, gently submerge the chicken thighs into the water, lifting them in and out a few times. Once the water starts bubbling, cover with a lid and simmer on the lowest heat for 8-10 minutes. Turn off the heat and let it sit covered for 30 minutes.
After 30 minutes, transfer the cooked chicken thighs to an ice bath for 10 minutes to halt the cooking process and give the skin its desired texture. Reserve the poaching liquid (chicken stock) for later use. *To check for doneness, insert a toothpick into the thickest part of the drumstick, if the juices run clear, it's cooked through. Remove the chicken from the ice bath and drain well. Use a sharp knife to debone the chicken thighs.
In a rice cooker, combine jasmine rice with the reserved chicken stock (maintaininga ratio of 1 part rice to 1.25 parts liquid) and cook according to the rice cooker's instructions.
While the rice is cooking, prepare the dipping sauces.
Once the rice is ready, serve the sliced chicken alongside the cooked rice,accompanied by cucumbers (optional) and prepared dipping sauces. Enjoy your Hainan Chicken!