Preheat your oven to 400°F (200°C). In a large mixing bowl, combine ground meat, panko bread crumbs, egg, and minced garlic. Mix everything together until just combined, then shape the mixture into small, evenly-sized meatballs and place them on a baking sheet.
Bake the meatballs in the preheated oven for about 15-20 minutes, until they are golden and cooked through, with no pink remaining inside.
While the meatballs are baking, prepare the sauce. In a small saucepan, combine vinegar, soy sauce, brown sugar, and pineapple chunks. Bring the mixture to a gentle simmer, allowing the flavors to meld and the pineapple to warm up.
In a small bowl, whisk together water and cornstarch until smooth, then gradually stir this into the simmering sauce. Continue stirring until the sauce thickens and becomes glossy, about 2-3 minutes. Remove from heat.
Transfer the baked meatballs into the saucepan with the sweet and sour sauce. Gently spoon the sauce over each meatball, ensuring they are well coated, and cook for another 5 minutes over low heat to allow flavors to meld.
Arrange the finished meatballs on a serving platter or bowl, spooning extra sauce over the top. Serve hot with cooked rice or enjoy on their own, with the sauce pooling around for dipping if desired.