Combine ground beef, eggs, bread crumbs, garlic powder, and diced onion and mix well. Form into ¾" meatballs and place on a baking sheet.
Bake meatballs at 350˚F for 20 minutes.
Whisk garlic, ginger, Worcestershire sauce, brown sugar, vinegar, and soy sauce and set aside.
Cut the vegetables into 1-inch chunks, set aside.
In a large skillet over medium heat, cook onion with olive oil until slightly softened, about 3 minutes. Add peppers and cook an additional 2-3 minutes.
Stir in the pineapple with juices, meatballs, and sauce mixture along with ¼ cup water. Simmer 5 minutes to allow flavors to combine.
Create a slurry with the cornstarch and water and add just enough to thicken as desired. You may not need all of the slurry. Serve over rice.
