In a medium bowl, whisk together the soy sauce, honey, olive oil, minced garlic, ground ginger, black pepper, salt, apple cider vinegar, and sesame oil until well combined.
Place the chicken thighs in a large resealable plastic bag or a shallow dish. Pour the marinade over the chicken, ensuring all pieces are well coated. Seal the bag or cover the dish and refrigerate for at least 1 hour, or up to 8 hours for more flavor.
Preheat your grill to medium-high heat.
Remove the chicken from the marinade and let any excess drip off. Discard the marinade.
Grill the chicken thighs for about 6-7 minutes on each side, or until they reach an internal temperature of 165°F and have nice grill marks.
Remove the chicken from the grill and let it rest for 5 minutes before slicing.
Garnish with chopped green onions if desired and serve warm.