Prepare the barbecue or smoker for indirect cooking over low heat (120°–150°C/250°–300°F). In a small bowl, mix together all the rub ingredients. Brush the chicken wings lightly with olive oil. Season them evenly with the rub.
Brush the cooking grates clean. Add the wood chunks to the coals (or drain and add the wood chips to the smoker box) and close the lid. When smoke appears, arrange the wings, skin side down, on the grates and roast over roasting/indirect low heat, with the lid closed, for 1 hour.
Meanwhile, make the glaze: in a small saucepan, warm the sesame oil over a medium heat on the stove. Add the garlic and ginger and cook for 30–60 seconds, stirring constantly. Add the remaining glaze ingredients, mix well and cook for 1–2 minutes, until simmering. Set aside off the heat.
After the first hour of cooking the wings, cut into one at the joint to check for doneness. The meat should no longer be pink at the bone. If it is pink, let the wings cook for another 30 minutes before you glaze them.
Brush the wings all over with the glaze and cook until the glaze has penetrated the surface of the wings, about 30 minutes. Transfer the wings to a platter and garnish with the spring onions, if using. Serve warm.
