In a large mixing bowl, combine the ground beef, breadcrumbs, finely chopped onion, eggs, and garlic powder. Gently mix until just combined, then shape into 1-inch meatballs.

Preheat your air fryer to 380°F or your oven to 400°F. Cook meatballs in air fryer for 10 minutes or bake in the oven for 20-25 minutes until browned.

In a medium bowl, whisk together rice vinegar, brown sugar, chicken broth, ketchup, tomato paste, pineapple juice, and cornstarch until smooth.

Heat oil in a skillet, add sliced bell peppers and onion, cook for 1 minute, then add minced garlic and cook for another 30 seconds.

Pour the sauce over the sautéed vegetables, stirring for 2-3 minutes until thickened. Add in the cooked meatballs and pineapple chunks, tossing to coat.

Serve over rice or noodles, or as appetizers with toothpicks.