01 - Preheat oven to 400°F. Line a baking sheet with parchment paper or lightly grease it.
02 - In a large bowl, combine ground chicken, breadcrumbs, egg, green onions, garlic, soy sauce, ginger, black pepper, and salt. Mix gently until just combined, being careful not to overwork the meat.
03 - Roll the mixture into 1-inch meatballs and arrange them on the prepared baking sheet. Bake for 18-20 minutes until cooked through and lightly golden on the outside.
04 - While the meatballs bake, combine pineapple juice, soy sauce, rice vinegar, brown sugar, and ketchup in a saucepan over medium heat. Bring to a gentle simmer.
05 - Dissolve cornstarch in water in a small bowl. Whisk the slurry into the simmering sauce and cook for 2-3 minutes, stirring constantly, until the sauce thickens and coats the back of a spoon.
06 - Stir the drained pineapple chunks into the thickened sauce and simmer for another 2 minutes to heat through.
07 - Transfer the baked meatballs into the saucepan, tossing gently to coat each meatball evenly. Cook for 2-3 minutes over low heat until everything is heated through.
08 - Serve hot, garnished with fresh cilantro or parsley, over steamed rice or noodles if desired.