Preheat your oven to 400°F (200°C).
In a large mixing bowl, combine the ground beef, breadcrumbs, Parmesan cheese, chopped green onions, egg, garlic, ginger, black pepper, and salt. Mix until well combined.
Shape the mixture into 1-inch meatballs and place them on a baking sheet lined with parchment paper. Bake in the preheated oven for 20 minutes or until cooked through.
While the meatballs are baking, prepare the sauce. In a medium saucepan, combine the soy sauce, brown sugar, cornstarch, vegetable oil, and water. Stir well and bring to a simmer over medium heat. Cook for about 5 minutes, stirring frequently, until the sauce thickens.
Once the meatballs are done baking, remove them from the oven and transfer them to the saucepan with the sauce. Gently toss to coat the meatballs in the sauce.
Serve the meatballs warm, garnished with additional chopped green onions.