In a small saucepan combine the soy sauce, sherry, chicken stock, ginger, garlic powder and spring onions. Bring to a boil and immediately remove from heat. Set aside.
Preheat the grill. Thread chicken pieces onto metal or bamboo skewers. Arrange on a pan that has been coated with cooking spray. Spoon 1 or 2 tablespoons of the sauce over each chicken skewer.
Place the pan under the grill and cook for about 3 minutes until browned. Remove from the oven, turn over and spoon more sauce onto each one. Return to the oven until chicken is cooked through and nicely browned.