In a bowl, mix ground beef, garlic, ginger, green onions, breadcrumbs, egg, and 1 tbsp soy sauce until combined.
Form mixture into 1-inch meatballs.
Heat vegetable oil in a large skillet over medium heat. Add meatballs and cook until browned on all sides, about 6-8 minutes.
In a small bowl, whisk together remaining soy sauce, brown sugar, water, and cornstarch.
Pour sauce into skillet with meatballs. Simmer until sauce thickens and meatballs are cooked through, about 5 minutes.
Serve meatballs with sauce over rice or noodles.