1.Preheat the grill for 10 minutes, preparing to grill over moderately high heat, and soak skewers in water.
2.In a bowl, use your hands to mix together all of the ingredients except for Honey Ginger balsamic vinegar, the sesame seeds, scallions and rice.
3.Form the meat mixture into 16 meatballs. Thread the meatballs onto the skewers, leaving just a little space in between and flatten slightly.
4.Oil the grates well and grill the meatball skewers until light grill marks form, 3 to 4 minutes. Flip and grill for 2 minutes longer, until outside of meatballs looks cooked.
5.Brush the Honey Ginger balsamic vinegar over the meatballs, flip and brush the other side. Flip them and brush them with the Honey Ginger balsamic vinegar for about 1 minute, until glazed and cooked through. If the glaze darkens too quickly, reduce the heat or move the skewers to a cooler part of the grill.
6.Transfer the skewers to a platter and sprinkle with sesame seeds and sliced scallions. Serve over rice, if desired.