Combine the soy sauce, mirin, ginger, sugar, pepper and sake in a small saucepan over medium heat. Bring to a simmer, stirring occasionally to dissolve sugar.

Simmer for 3-5 minutes until marinade thickens slightly. Set aside to cool

Place the chicken and mushrooms into separate bowls then pour 2 tbs of the soy marinade over the chicken and the remaining over mushrooms, stir to coat.

Cover and refrigerate for 1 hour or longer if time permits

Drain the chicken, discarding the marinade. Thread the chicken, mushrooms and green onions onto skewers

Preheat a barbecue grill or plate on medium heat.

Cook the skewers, turning and basting occasionally with marinade from mushrooms for 12-15 minutes or until chicken is cooked through

Serve with cabbage salad and/or rice