Preheat oven to 400°F (200°C).
In a mixing bowl, combine ground beef, breadcrumbs, beaten egg, minced garlic, soy sauce, sesame oil, and chopped green onions. Mix well.
Form the mixture into meatballs and place them on a baking sheet.
Bake in preheated oven for 15-20 minutes, or until cooked through.
While the meatballs are baking, prepare the glaze by combining soy sauce, brown sugar, rice vinegar, gochujang, and sesame oil in a small saucepan. Heat over medium heat until the sugar is dissolved and the sauce is slightly thickened.
Once the meatballs are done, toss them in the glaze until well coated.