In a large mixing bowl, combine the ground beef (or turkey), breadcrumbs, finely chopped green onions, beaten egg, soy sauce, garlic powder, ginger powder, and black pepper. Using your hands or a spatula, mix until everything is well incorporated and you have a cohesive mixture.
With clean hands, roll the mixture into small meatballs, about 1 inch in diameter. Arrange the meatballs neatly on a baking sheet lined with parchment paper, ensuring they are spaced apart.
Preheat your oven to 400°F (200°C). Once the oven reaches the desired temperature, bake the meatballs for 15-20 minutes. They should be nicely browned and cooked through (internal temperature should reach 165°F for beef or turkey).
While the meatballs are baking, prepare the teriyaki sauce. In a saucepan set over medium heat, combine the reserved pineapple juice, teriyaki sauce, and cornstarch. Whisk continuously until the sauce begins to thicken, which should take about 2-3 minutes.
Stir in the crushed pineapple into the thickened sauce, mixing well to ensure it is heated through. Let it simmer gently for another minute to meld the flavors.
Once the meatballs are finished baking, remove them from the oven and transfer them to a large mixing bowl. Gently pour the pineapple teriyaki sauce over the meatballs and toss gently until they are thoroughly coated in the delicious glaze.
Serve the meatballs on a decorative platter, sprinkling sesame seeds and extra chopped green onions on top for a fresh and vibrant touch.
Notes
Serve with steamed rice or an Asian slaw for a complete meal.