01 - Preheat oven to 400°F. Line a baking sheet with parchment paper or lightly grease with cooking spray.
02 - Combine ground chicken or turkey, breadcrumbs, egg, green onions, garlic, ginger, soy sauce, salt, and black pepper in a large bowl. Mix gently until just combined, avoiding overworking the meat.
03 - Roll the mixture into 1-inch meatballs and arrange on the prepared baking sheet, spacing evenly for consistent cooking.
04 - Bake for 15-18 minutes until cooked through and lightly golden on the exterior. An instant-read thermometer should register 165°F when inserted into the center.
05 - Whisk together pineapple juice, water, brown sugar, soy sauce, rice vinegar, and cornstarch in a small bowl until completely smooth and dissolved.
06 - Heat vegetable oil in a large skillet over medium heat. Sauté red bell pepper for 2 minutes, then add pineapple chunks and cook for an additional 2 minutes until slightly softened.
07 - Pour the pineapple sauce mixture into the skillet. Bring to a simmer, stirring constantly until the sauce thickens and coats the back of a spoon, approximately 3-4 minutes.
08 - Add baked meatballs to the thickened sauce and toss gently to coat evenly. Simmer for 2-3 minutes until heated through. Serve immediately over steamed rice, garnished with additional green onions or sesame seeds if desired.