Peel the ginger using the edge of a spoon. Grate finely using a microplane for maximum flavor extraction.
Mince garlic and allow to rest for 10 minutes before adding to other ingredients to develop allicin compounds.
In a bowl, whisk together soy sauce, rice vinegar, sesame oil, and honey until fully incorporated and honey is dissolved.
Stir in the prepared ginger, garlic, sliced green onions, black pepper, and red pepper flakes if using.
Whisk all ingredients until uniformly combined with aromatics evenly distributed.
Pour marinade over 1-1.5 pounds (450-680g) of chicken in a sealed container or zip-top bag, ensuring all surfaces are coated.
Refrigerate and marinate according to cut: boneless breasts (30 min to 6 hours), bone-in breasts (1 to 12 hours), boneless thighs (45 min to 12 hours), bone-in thighs (1 to 24 hours).