Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.
In a large mixing bowl, combine ground beef (or turkey), breadcrumbs, green onions, minced garlic, grated ginger, soy sauce, sesame oil, egg, salt, pepper, and brown sugar if desired. Mix until well combined.
Form the mixture into small meatballs about one inch in diameter and place them on the prepared baking sheet.
Bake for about 20–25 minutes or until cooked through and golden brown.
Mix together mayonnaise, Sriracha, lemon juice, and soy sauce in a small bowl.
Garnish the dip with sesame seeds and chopped green onions if desired.
Serve the meatballs warm alongside the spicy mayo dip.