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 mixture.
03 - Roll the mixture into 1-inch meatballs and arrange them evenly on the prepared baking sheet.
04 - Bake for 18 to 20 minutes, until the meatballs are cooked through and lightly golden on the outside.
05 - 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, stirring occasionally.
06 - Dissolve cornstarch in water in a small bowl, then whisk the slurry into the simmering sauce. Cook for 2 to 3 minutes, stirring constantly, until the sauce thickens and coats the back of a spoon.
07 - Stir the drained pineapple chunks into the thickened sauce and simmer for another 2 minutes to heat through.
08 - Transfer the baked meatballs into the saucepan, tossing gently to coat each meatball evenly. Let them warm through for 2 to 3 minutes.
09 - Serve hot, garnished with fresh cilantro or parsley, alongside steamed rice or noodles.