Preheat your oven to 400°F.
In a large bowl, combine the ground beef, panko breadcrumbs, green onions, garlic, soy sauce, sesame oil, ginger, black pepper, and salt. Mix until just combined.
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 the mayonnaise, gochujang, 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 for a few minutes.
Serve the meatballs warm with the spicy mayo dip on the side.