Rinse the chicken well. Remove excess fat from the chicken and set aside. If using chicken thighs, trim off the excess fat from the underside by cutting and scraping, If using a whole chicken, you can cut fat from the back cavity.
Lightly rub the chicken with coarse or kosher salt to exfoliate it. Keep rubbing till you get all the loose skin off and the skin shines. Rinse the chicken under running water to remove the salt, and pat dry.
Fill a stock pot with water and add chicken. Ensure that the water covers the chicken. If using a whole chicken, place the chicken such that the breast side faces down. Leave to boil.
Add green onions and ginger into the pot.
Once the soup boils, turn the chicken over. If using full chicken, turn it over so the breast side is on top. Remove some water from the stock pot so that the chicken breast just peeps out of the water. (This is because breast cooks faster than other parts of chicken, and may dry out if overcooked.)
Cover the pot and let the stock / broth simmer for around 20 minutes.
Close to the 20 minute mark, prepare a large bowl of ice water.
Remove the chicken from the pot, but don't switch the stove off. Let the stock continue simmering. Dip the chicken in the ice bath for 15 seconds and then keep it aside.
Mix sesame oil and salt to prepare the glaze for the chicken. Coat this on the skin of chicken. (I use a basting brush for this)
Continue simmering the broth for at least 40 minutes. The more you simmer, the tastier the broth.
Taste, and add salt and pepper, if required.