Combine the pork, panko, the remaining 1 tablespoon hoisin sauce, the scallion, ginger, 1/2 teaspoon salt, and a few grinds of black pepper in a medium bowl. With damp hands, roll the mixture into twelve 1 1/2 inch meatballs; transfer to the prepared baking sheet. Bake, turning once, until browned and cooked through, 5-6 minutes per side. Remove from the oven and brush with reserved hoisin sauce mixture.