01 - In a small saucepan, combine soy sauce, mirin, sake, sugar, minced garlic, and grated ginger. Bring to a gentle boil over medium heat, stirring until sugar dissolves. Reduce the heat and simmer for 5 to 7 minutes until the sauce thickens slightly. Allow to cool before use.
02 - Thread chicken thigh pieces and spring onion segments alternately onto pre-soaked bamboo skewers.
03 - Brush the grill or a griddle pan lightly with vegetable oil and preheat over medium-high heat.
04 - Arrange skewers on the hot grill. Cook for 3 to 4 minutes per side, frequently brushing with tare sauce, until the chicken is cooked through and has a glossy glaze.
05 - Transfer skewers to a serving platter and offer additional tare sauce alongside if desired. Serve hot.