01 - In a small saucepan, combine soy sauce, mirin, sake, sugar, garlic, and ginger. Bring to a gentle boil over medium heat, stirring until the sugar dissolves. Reduce heat and simmer for 5-7 minutes until slightly thickened. Remove from heat and let cool.
02 - Thread chicken and scallion pieces alternately onto the soaked bamboo skewers, distributing them evenly.
03 - Brush a grill or griddle pan with vegetable oil and preheat over medium-high heat until hot.
04 - Arrange the skewers on the grill and cook for 3-4 minutes on each side, brushing generously with the tare sauce as they cook, until the chicken is cooked through and achieves a glossy, caramelized glaze.
05 - Transfer to a platter and serve hot with extra tare sauce on the side.