Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper.

In a large mixing bowl, combine the ground pork, Panko breadcrumbs, beaten egg, 2 tbsp soy sauce, grated ginger, minced garlic, 2 tbsp sliced green onions, and black pepper. Mix gently but thoroughly until just combined, being careful not to overmix, which can make meatballs tough.

Roll the mixture into 1-inch size meatballs (approximately 30-36 meatballs) and place them evenly spaced on the prepared baking sheet.

Bake for 15-20 minutes, or until the meatballs are cooked through and lightly browned. Set aside.

While the meatballs are baking, heat sesame oil in a large pot or Dutch oven over medium heat. Add the chopped onion and bell peppers. Sauté for 5-7 minutes until the vegetables start to soften. Add the minced garlic and grated ginger, and cook for another minute until fragrant.

Pour in the chicken broth, rice vinegar, pineapple juice, brown sugar, ketchup, 2 tbsp soy sauce, and Worcestershire sauce. Whisk well to combine, ensuring the brown sugar is dissolved.

Bring the mixture to a gentle simmer. Add the drained pineapple chunks. Reduce heat to low, cover, and let simmer for 5-7 minutes to allow the flavors to meld.

In a small bowl, whisk together the cornstarch and cold water until a smooth slurry forms.

Slowly pour the cornstarch slurry into the simmering soup, whisking continuously. Continue to simmer for 2-3 minutes, stirring occasionally, until the soup thickens to your desired consistency.

Gently add the cooked meatballs into the thickened sweet and sour soup. Stir gently to coat the meatballs and allow them to heat through for 2-3 minutes.

Ladle the tangy sweet and sour meatball soup into bowls. Garnish with sliced green onions and sesame seeds, if desired. Serve hot, perhaps with a side of steamed rice or noodles.