Preheat the oven to 400°F (200°C) and line a baking sheet with parchment paper.
In a large mixing bowl, combine the ground chicken, breadcrumbs, green onions, minced garlic, ginger paste, beaten egg, sesame oil, salt, and pepper. Mix until all ingredients are well incorporated.
Using your hands, shape the mixture into 1-inch meatballs and place them on the prepared baking sheet.
Bake the meatballs in the preheated oven for 20 minutes or until they are cooked through and golden brown.
While the meatballs are baking, prepare the sweet and sour sauce. In a saucepan over medium heat, combine pineapple juice, rice vinegar, ketchup, brown sugar, and soy sauce. Bring the mixture to a gentle boil.
Once boiling, reduce the heat and stir in the cornstarch slurry. Cook for an additional 2-3 minutes, or until the sauce thickens slightly.
Remove the meatballs from the oven and transfer them to a serving bowl. Pour the sweet and sour sauce over the meatballs and gently toss to coat.
Serve the sweet and sour chicken meatballs warm, garnished with extra green onions or sesame seeds if desired.
Notes
Garnish with extra green onions or sesame seeds if desired.