In a large mixing bowl, combine ground beef, panko breadcrumbs, egg, soy sauce, sesame oil, garlic, and ginger. Mix with sliced green onions and form into meatballs.

Shape the mixture into 1-inch meatballs, yielding around 20 meatballs.

Heat vegetable oil in a large skillet over medium heat until shimmering. Add meatballs in a single layer.

Cook for 5-7 minutes, turning occasionally until golden brown and cooked through.

In a small bowl, whisk together gochujang, brown sugar, rice vinegar, and water.

Pour glaze over cooked meatballs and toss gently to coat, cooking for an additional 2-3 minutes.

Transfer to a serving platter and garnish with remaining green onions and sesame seeds.