01 - In a mixing bowl, whisk together soy sauce, mirin, brown sugar, honey, rice vinegar, sesame oil, garlic, and ginger until well combined.
02 - Set aside 3 tablespoons of the marinade in a small bowl for glazing.
03 - Place chicken cubes in a large bowl or zip-top bag and pour remaining marinade over. Toss to evenly coat. Cover and refrigerate for at least 30 minutes and up to 2 hours.
04 - If using wooden skewers, soak them in water for 30 minutes to prevent burning during cooking.
05 - Thread marinated chicken pieces onto skewers, distributing meat evenly.
06 - Preheat grill or broiler to medium-high heat.
07 - Arrange skewers on the grill or under the broiler and cook for 12 to 15 minutes, turning occasionally, until the chicken is cooked through and slightly charred.
08 - Pour reserved marinade into a small saucepan. Bring to a simmer over medium heat for 2 to 3 minutes. For a thicker glaze, mix cornstarch with a tablespoon of water, stir into marinade, and cook until thickened.
09 - Remove skewers from heat and brush cooked chicken generously with teriyaki glaze.
10 - Sprinkle with toasted sesame seeds and sliced spring onions. Serve hot with steamed rice or grilled vegetables if desired.