Yakitori Chicken Skewers

6 scallion, cut into 4 cm pieces

10 g ginger root, peeled and sliced

2 garlic, halved

600 g chicken thigh, boneless, skin-on, cut into 2.5 cm chunks

120 ml soy sauce

80 ml mirin

60 ml sake

30 ml granulated sugar

10 ml sesame oil

5 ml black pepper, freshly ground