Combine the soy sauce, dry vermouth, sake, water, sugar, sesame oil, garlic and ginger in a small sauce pan. Bring the sauce to a boil and cook for about 15 minutes, or until the sauce coats the back of a spoon. Set sauce aside to cool. Reserve about 1/3 cup of the marinade to serve with the chicken.

Soak about 8-10 wooden skewers for about 30 minutes while you cut up the chicken. Place the chicken thigh pieces in a large bowl. Pour the marinade over the chicken and toss to coat. You can cover and refrigerate the chicken for a couple of hours while it marinates.

When you're ready to cook the chicken, thread the chicken onto the skewers. Oil your grill grates or pre-heat the oven to 450 degrees F. Grill the skewers for about 8 minutes or until the internal temperature reaches 165 degrees F. If baking in the oven, cook for about 12-15 minutes or until the internal temperature reaches 165 degrees F. Garnish with sliced scallions.