Preheat the oven to 400°F (200°C) and line a baking sheet with parchment paper.

In a large mixing bowl, combine ground beef, panko breadcrumbs, egg, soy sauce, gochujang, sesame oil, minced garlic, grated ginger, and chopped green onion.

Mix until well combined, then form into 1-inch meatballs and place them on the prepared baking sheet.

Bake the meatballs in the preheated oven for 15-20 minutes, or until cooked through and browned on the outside.

Remove from the oven and sprinkle with sesame seeds before serving.

In a small bowl, mix together mayonnaise, gochujang, lime juice, and sriracha (if using) until smooth.

Serve the meatballs warm with the spicy mayo dip on the side for dipping.