01 - In a mixing bowl, whisk together soy sauce, mirin, brown sugar, honey, rice vinegar, sesame oil, minced garlic, and grated ginger until the sugar dissolves and the mixture is well combined.
02 - Measure out 3 tablespoons of the marinade and set aside for glazing the skewers later.
03 - Place the chicken cubes in a large bowl or zip-top bag. Pour the remaining marinade over the chicken and toss to coat evenly. Refrigerate for at least 30 minutes, or up to 2 hours for deeper flavor penetration.
04 - If using wooden skewers, submerge them in water for 30 minutes to prevent burning during cooking.
05 - Remove chicken from the marinade, allowing excess to drip off. Thread the cubes onto skewers, leaving a small gap between pieces for even cooking.
06 - Heat grill or broiler to medium-high, approximately 400°F.
07 - Grill or broil the skewers for 12 to 15 minutes, turning occasionally, until the chicken is cooked through (internal temperature reaches 165°F) and lightly charred on the edges.
08 - While the skewers cook, pour the reserved marinade into a small saucepan and bring to a simmer over medium heat for 2 to 3 minutes. For a thicker glaze, dissolve cornstarch in a splash of water, stir into the saucepan, and cook until the desired consistency is reached.
09 - Brush the cooked skewers generously with the teriyaki glaze. Garnish with toasted sesame seeds and sliced spring onions. Serve immediately alongside steamed rice or grilled vegetables.