Tofu Japanese Skewers

Name: Tofu Japanese Skewers
Ingredients: 1 kg pack of super firm Tofu, drained, pressed and cut into 24 cubes; 8 spring onions, cut into 1cm pieces; 3 1/2 Tbs brown sugar; 16 skewer sticks, soaked in water overnight; Salt and pepper to taste; Marinade:; 1/2 cup water; 1/4 cup mirin (rice cooking wine); 1/4 cup tamari; 2 Tbs sake; 2 tsp brown sugar; 1/4 tsp ground pepper; 2 spring onions, roughly chopped; 1 ginger, minced; 1 clove garlic, roughly chopped