Creating these delectable Teriyaki Meatballs is simple if you follow these steps:

1. Preheat the Oven: Set your oven to 400°F (200°C) and prepare a baking sheet lined with parchment paper.
2. Mix Ingredients: In a large bowl, combine the ground beef or turkey, breadcrumbs, green onions, egg, minced garlic, grated ginger, soy sauce, brown sugar, sesame oil, and black pepper.
3. Form the Meatballs: Use your hands to mix everything until just combined. Shape the mixture into meatballs, each about 1 inch in diameter. Place them on the prepared baking sheet.
4. Bake the Meatballs: Bake in the preheated oven for 15-20 minutes or until they are cooked through and slightly browned.
5. Prepare the Teriyaki Glaze: While the meatballs are baking, combine teriyaki sauce and a splash of water in a small saucepan over medium heat. Bring it to a gentle simmer, and let it thicken slightly.
6. Glaze the Meatballs: Once cooked, remove the meatballs from the oven and brush them generously with the teriyaki glaze. Place them back in the oven for an additional 5 minutes.
7. Garnish and Serve: Once they are out of the oven, sprinkle sesame seeds and extra green onions over the top. Serve hot!

These clear instructions ensure that even novice cooks can create mouthwatering Teriyaki Meatballs with ease.