In a mixing bowl, combine the small pieces of sandwich bread and milk. Let them soak for about 5 minutes until the bread is soft. Then, add in the ground beef, finely diced onion, grated garlic, egg, salt, and black pepper. Mix well until all ingredients are thoroughly combined.
Using your hands, shape the mixture into meatballs, about 1-inch in diameter. Place the formed meatballs onto a baking sheet, ensuring they are spaced evenly apart.
Preheat your oven to 375°F (190°C). Bake the meatballs for 20-25 minutes, or until they are browned and cooked through. You can also switch to the broiler for a couple of minutes at the end for a nice caramelization on top.
While the meatballs are baking, prepare the sauce. In a saucepan over medium heat, combine the ketchup, mustard, water, diced onion, grated garlic, salt, black pepper, Worcestershire sauce, and brown sugar. Stir until the sugar dissolves and the sauce is heated through.
Once the meatballs are done baking, transfer them to the saucepan with the sweet and sour sauce. Gently stir to coat the meatballs evenly in the sauce. Allow them to simmer for an additional 5-10 minutes to enhance the flavors.
Serve the meatballs hot, garnished with diced green onions. They pair perfectly with steamed rice or noodles, making for a complete meal that delights everyone at the table.
