Prepare scallions as you'll be using them in three different ways. Tie 1/3 into a knot; chop another 1/3 into matchstick sizes; then finally dice the remaining 1/3 finely.
Into a pot of water, add knotted scallions and half of ginger. Bring water to a boil, then add chicken and let cook for 5-10 minutes.
Turn off heat and allow chicken to continue sitting in the hot water for another 10-15 minutes until fully cooked. The time varies depending on the size of your chicken.
Remove chicken from pot and set aside. Once cool enough to handle, shred chicken meat with hand.
In a bowl, mix soy sauce and oyster sauce with the shredded chicken. Plate the chicken. Sprinkle chopped scallions on top.
Heat oil in a pan and add in scallion matchsticks, shallots and remaining ginger. Let simmer over low heat for 10-15 minutes to infuse oil with the aromatics' flavour. When scallions are browned at the edges, you can turn off heat. Remove scallions, shallots and ginger from aromatic oil. Reserve 1 tbsp of oil and keep the rest for later use. You can fry egg, rice or meat in it.
While still hot, pour the reserved 1 tbsp of aromatic oil over the scallions which you scattered on top of the chicken in Step 5. The heat will remove the scallions' raw flavour and bring out the aroma. Mix thoroughly until chicken is well coated. Serve with hot rice.