Put water into a large pot, add sliced ginger root and leek, and bring to boil.
Add chicken breasts, turn off the heat, and leave it for an hour.
In the meantime, mix the sauce ingredients together (except for water used for poaching) and chop scallions.
Once chicken is done, take them out, and slice them into small pieces.
Add the water used for poaching into the sauce mix.
Put chicken on a plate, garnish it with scallions, and pour the sauce on top. (I love eating this with some lettuce, so I usually chop some romaine lettuce and put the chicken on top of that!)