Preheat the oven to 400°F.
In a large bowl, combine ground beef, breadcrumbs, green onions, soy sauce, sesame oil, garlic, ginger, black pepper, egg, and brown sugar. Mix until well combined.
Using your hands, form the mixture into meatballs about 1 inch in diameter and place them on a baking sheet lined with parchment paper.
Bake for 15-20 minutes or until cooked through and browned.
While the meatballs are baking, prepare the spicy mayo dip by whisking together mayonnaise, sriracha, lime juice, and sesame oil in a small bowl until smooth.
Once the meatballs are done, remove them from the oven and let them cool slightly before serving with the spicy mayo dip.