01 - Whisk together soy sauce, mirin, brown sugar, honey, rice vinegar, sesame oil, minced garlic, and grated ginger in a bowl until well combined.
02 - Set aside 3 tablespoons of marinade in a separate cup for glazing.
03 - Combine chicken cubes and remaining marinade in a large bowl or zip-top bag. Mix thoroughly and refrigerate for at least 30 minutes, or up to 2 hours for enhanced flavor.
04 - Soak wooden skewers in water for 30 minutes to prevent burning if using them. Thread marinated chicken pieces onto skewers.
05 - Preheat grill or broiler to medium-high heat. Place skewers on the grill and cook for 12 to 15 minutes, turning occasionally, until chicken is thoroughly cooked and edges are slightly charred.
06 - Pour reserved marinade into a small saucepan. Bring to a simmer over medium heat for 2 to 3 minutes. For a thicker glaze, add cornstarch dissolved in a splash of water and cook until glossy and thickened.
07 - Brush cooked chicken skewers with warm teriyaki glaze. Arrange on a platter, sprinkle with toasted sesame seeds and sliced spring onions. Serve immediately with cooked rice or grilled vegetables if desired.