Mix the brown sugar, mirin, sake, soy sauce, vinegar, ginger and garlic granules in a medium bowl. Reserve half for the glaze.
Place the chicken wings in a large re-sealable plastic bag and add the remaining half of the marinade, turning so they are well coated. Refrigerate for 30 minutes or longer for extra flavour.
Stir the cornflour into the reserved marinade and bring to the boil in a small saucepan. Reduce the heat to a low simmer for 2 minutes, then remove from the heat and cool for 5 minutes. Stir in Wasabi Furikake Seasoning then pour the glaze into a large bowl and set aside.
Remove the wings from the marinade and discard any remaining marinade. Thread the wing pieces onto skewers. Grill the wings over a medium heat 20-25 minutes or until they are cooked through, turning occasionally.
Brush the wings with the reserved glaze. Sprinkle with the additional Wasabi Furikake Seasoning and spring onions before serving.
