Prepare Sauce: Combine soy sauce, ketchup, chicken broth, brown sugar, honey, ginger, garlic, and sesame oil in a mixing bowl.
Marinate Chicken: Place chicken thighs in a large dish and pour half of the sauce over the chicken, reserve the rest. Marinate for at least 30 minutes.
Preheat Grill: Heat the grill to medium-high heat.
Grill Chicken: Place chicken on the grill, skin side down first, and grill for about 10 minutes on each side, while basting with the reserved sauce.
Serve: Remove chicken from grill and garnish with chopped green onions. Serve hot.