2 pounds scallops should give you 5-6 skewers, but the complete recipe can be doubled to 4 pounds, but each 2-pounds scallops will have to be marinated in two plastic bags using two rice wine/ginger mixtures.
In a bowl stir together the rice wine with 1 tablespoon fresh ginger, then pour the mixture into a ziploc resealable plastic bag, add in the scallops seal bag then turn to coat with the mixture.
Chill scallops for 35 minutes (no longer than stated time or the rice wine will start to "cook" the scallops!).
Meanwhile soak 6 (12-inch) wooden skewers in cold water for 30 minutes minimum.
In a saucepan combine the brown sugar, ketchup, broth, rice vinegar, soy sauce, cornstarch, sesame oil, minced garlic and red pepper flakes (if using) bring to a boil over medium heat, stirring constantly, boil for 1 minute; set aside.
Remove scallops and discard the marinade.
Thread scallops leaving about 1/2-inch apart onto the soaked wooden skewers.
Grill over medium heat for 2-3 minutes on each side (time will vary depending on the size of your scallops).
Brush scallops with the prepared brown sugar sauce, then serve immediately with remaining sauce.