Mince ginger and garlic in food processor. Add scallions, pulse until finely chopped. In a shallow dish, combine this mixture and 3 tablespoons of soy sauce and oil. Add chicken, turn until completely coated. Cover and marinate in fridge for 20 minutes to an hour. In a small bowl, combine peanut butter, broth and remaining 2 tablespoons soy sauce, red pepper flakes and sugar. Set aside. Grill chicken till done. Serve with peanut sauce, rice or steamed veggies of your choice.