Preheat your oven to 400°F.
In a large mixing bowl, combine the ground beef, breadcrumbs, green onions, garlic, soy sauce, sesame oil, ginger, black pepper, and salt. Mix until well combined.
Form the mixture into meatballs, about 1 inch in diameter, and place them on a baking sheet lined with parchment paper.
Bake in the preheated oven 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, Sriracha, lime juice, and garlic powder until smooth.
Once the meatballs are done, remove them from the oven and brush with hoisin sauce for a glossy finish. Return to the oven for an additional 5 minutes.
Serve the meatballs hot with the spicy mayo dip on the side. Garnish with extra green onions if desired.