01 - Preheat oven to 400°F and line a baking sheet with parchment paper or lightly grease it.
02 - In a large bowl, combine ground beef, egg, breadcrumbs, milk, garlic, green onions, Sriracha, soy sauce, sesame oil, black pepper, and salt. Mix until just combined, avoiding overworking.
03 - Shape the mixture into 20 uniform meatballs and place them evenly spaced on the prepared baking sheet.
04 - Bake for 18 to 20 minutes until cooked through and golden brown.
05 - While baking, combine Sriracha, honey, soy sauce, and rice vinegar in a small saucepan over medium heat. Bring to a simmer, then whisk in butter until melted and sauce is glossy. Remove from heat.
06 - Transfer baked meatballs to a large bowl, pour the hot sauce over them, and toss gently to coat evenly.
07 - Sprinkle with sesame seeds and sliced green onions. Serve warm as an appetizer or alongside rice for a main course.