In a mixing bowl, combine chicken thighs with soy sauce, dark soy sauce, black pepper powder, and corn starch. Mix until fully coated, then allow to marinate for 10 minutes.

Wash and slice the scallions, separating the white parts from the green tops.

Heat a non-stick skillet over medium heat and add oil, heating until shimmering (about 1-2 minutes).

Add the marinated chicken to the hot pan and cook undisturbed for 5-7 minutes until golden brown.

Once chicken is cooked through, add the white parts of the scallions and cook for an additional 2-3 minutes.

Finally, add the green tops of the scallions and stir for 10-20 seconds until just wilted.

Transfer the scallion chicken to a serving platter and serve with rice or noodles.