Preheat oven to 400°F (200°C) and line a baking sheet with parchment paper.
In a small bowl, combine the panko and milk and let sit for 5 minutes to soften.
In a large bowl, combine the ground chicken, soaked panko, egg, garlic, salt, pepper, and green onion. Mix gently until just combined.
Roll the mixture into about 16-18 meatballs (roughly 1.5 inches each) and place on the baking sheet.
Bake for 18-20 minutes, until cooked through and the internal temperature reaches 165°F.
While the meatballs bake, combine the honey, soy sauce, garlic, rice vinegar, and red pepper flakes (if using) in a small saucepan. Simmer over medium heat for 3-4 minutes, until slightly thickened.
Toss the baked meatballs in the glaze until evenly coated.
Serve over rice with extra glaze spooned over top and a sprinkle of green onion.