Preheat the oven to 450 degrees Fahrenheit. Line a baking sheet with parchment paper and set aside.
To a large bowl, add 1 pound ground beef, 1 small finely minced onion, ½ cup breadcrumbs, 1 egg, 3 teaspoons minced garlic, 1 teaspoon salt, and ½ teaspoon pepper. Mix until evenly combined.
Scoop the meatball mixture into 2 tablespoon-sized balls and roll them into smooth balls. You should get 18-20 meatballs. Place them on the baking sheet and spray them lightly with oil.
Bake the meatballs for 18 minutes, until they are fully cooked, rotating them halfway through.
In a small bowl, whisk together ½ cup pineapple juice, ½ cup brown sugar, ⅓ cup apple cider vinegar, ¼ cup water, ¼ cup ketchup, 1 tablespoon soy sauce, 1 tablespoon sriracha, and 1 tablespoon cornstarch.
In a large wok or pan, heat 1 tablespoon vegetable oil over high heat. Add 1 green bell pepper, 1 red bell pepper, and 1 small onion. Cook for 2 minutes.
Reduce the heat to low, then add 1 cup pineapple chunks, meatballs, and sauce to the pan. Simmer the meatballs in the sauce for 4-5 minutes until the sauce thickens. Serve over rice.
Notes
Leftover and Make Ahead Instructions
Fridge- Store in an airtight container in the fridge for up to 5 days.
Reheat: Microwave or stovetop until heated through.
Freezer- Store in an airtight freezer-safe container for up to 3 months.
Make Ahead- Make the meatballs the day before and store them in the fridge until you are ready to cook them. You can also freeze the uncooked meatballs. Cook from frozen, adding a few extra minutes to the bake time.