Preheat your oven to 375°F (190°C) and line a baking sheet with parchment paper.
In a large mixing bowl, combine the ground beef, panko breadcrumbs, green onions, egg, soy sauce, brown sugar, garlic, sesame oil, ginger, and black pepper.
Mix well using your hands until all ingredients are evenly combined.
Shape the mixture into 1-inch diameter meatballs and place them on the lined baking sheet.
Bake the meatballs for 20-25 minutes, or until they are cooked through and lightly browned.
While the meatballs are cooking, prepare the Korean BBQ sauce by combining the soy sauce, brown sugar, garlic, sesame oil, and ginger in a skillet over medium heat.
Cook the sauce for 5-7 minutes, stirring occasionally, until it thickens.
Remove the meatballs from the oven and place them in the skillet with the sauce.
Gently toss the meatballs in the sauce until they are evenly coated.
Serve the Korean BBQ meatballs hot, garnished with sesame seeds and sliced green onions if desired.