In a large zipper-lock bag or bowl, combine fish sauce, brown sugar, and orange juice. Mix well. Add the chicken chunks, shake well to coat. Refrigerate for at least 2 hours or overnight.
In a medium saucepan, combine the brown sugar, fish sauce, orange juice, rice vinegar, and honey over medium heat. Stir until sugar dissolves. Add garlic, shallots, and ginger and continue to cook, stirring occasionally, until glaze becomes thick and sticky and easily coats the back of a spoon. Remove from heat and set aside.
Light one chimney full of charcoal. When all the charcoal is lit and covered with gray ash, pour out and spread the coals evenly over half of coal grate. Alternatively, set all the burners of a gas grill to high heat. Set cooking grate in place, cover grill, and allow to preheat for 5 minutes. Clean and oil the grilling grate. (I used a gas grill, on high heat until the chicken skewers went on. Then turned to low to cook throughly. Then back on high for a final seat)
Thread the chicken on 6 bamboo skewers. Transfer to the grill and cook over direct heat, turning and brushing with the glaze every 5 minutes until chicken is cooked through and crisp, about 8 minutes.
Remove from heat, garnish with scallions, and serve.