In a large bowl or zip-top bag, mix all the marinade ingredients (except cornstarch/water). Save half the marinade for later use. Brush the chicken wings with peanut oil and then add the chicken wings and toss to coat. Cover and refrigerate for at least 4 hours or overnight for the best flavor.
After marinating, preheat the grill. Set it up for indirect heating at about 350°F to 400°F. Grill over medium heat, turning frequently, for 20–25 minutes until browned and slightly charred.
While wings cook, pour the reserved marinade into a small saucepan. Bring to a boil, then reduce the heat. Stir in the cornstarch slurry and simmer until thickened (about 2–3 minutes). Use this as a glaze or dipping sauce. I prefer to use it as a glaze but either way is fine.
Brush wings with thickened glaze. Sprinkle with green onions. Serve hot as an appetizer or party dish!